NEW YORK — A 29-year-old man driving a rental truck plowed down people on a Manhattan bike path Tuesday in what authorities described as a terrorist attack that killed eight and injured 11 before the suspect was shot and arrested by police.
A sunny fall day along the Hudson River erupted in chaos just around the time students were getting out from nearby Stuyvesant High School, when a rented Home Depot truck turned on to the bike path along the West Side Highway.
Witnesses say the speeding truck struck unsuspecting bicyclists and pedestrians while onlookers screamed and scattered. The truck then veered left toward Chambers Street, where it collided with a small school bus, injuring two adults and two children inside, officials said.
According to a video from the scene, the man then jumped out of the wrecked vehicle brandishing what appeared to be handguns. Some witnesses said he shouted “Allahu akbar’’ meaning “God is great’’ in Arabic.
Law enforcement officials, speaking on the condition of anonymity to discuss an open investigation, identified the suspect as Sayfullo Saipov, an Uzbek immigrant who had been living in Tampa.
The attack could intensify the political debate over immigration and security. President Trump has argued for much tougher screening of immigrants to prevent terrorism, and opponents of those policies have sought to block his efforts in the courts. Uzbekistan was not among the countries named in any version of the president’s travel ban, which largely targeted a number of majority-Muslim countries.
Trump responded to the attack on Twitter, saying it “looks like another attack by a very sick and deranged person.’’ He tweeted a short time later: “We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!” ISIS is an acronym for the Islamic State.
There was no immediate indication that the attack had been directed by the Islamic State. However, the group has called on its supporters in Western countries to launch their own attacks, using anything at hand as weapons, including vehicles.
Inside the rental truck, investigators found a handwritten note in which Saipov had declared his allegiance to the Islamic State, according to officials.
Saipov is expected to survive, meaning investigators will likely have a chance to question him about his motive for the attack, but so far, they said, he appears to have been a “lone wolf’’ suspect – someone who acted alone after being inspired, but not directly instructed, by the Islamic State.
He had been living in Paterson, New Jersey before the attack, and rented the vehicle in that state before driving it into Manhattan, officials said.
The violence was terrifyingly similar to vehicle attacks carried out in Europe, where Islamic State supporters have used cars and trucks to strike pedestrians in crowded streets, a tactic that has been employed in France, Britain, Germany, Sweden and Spain.
“This certainly bears all the hallmarks of an ISIS-inspired or al-Qaeda-inspired attack,” said Rep. Adam B. Schiff (Calif.), the ranking Democrat on the House Intelligence Committee, whom the FBI briefed on the attack Tuesday evening. “We have to expect that as the capital of the caliphate has now fallen, there are going to be increasing efforts to show that they remain dangerous and lethal, and to expand the virtual caliphate. But at this point, we don’t know whether this was an ISIS-directed attack or merely someone acting out of radical inspiration.”
Antonio Valasquez, 28, said he saw the truck speed by as he left a restaurant and then heard a crash. “I didn’t really understand, you know, at first what was happening,” he said. Valasquez said he heard what appeared to be gunshots shortly after but couldn’t be sure. “I was running away.”
An officer from the 1st Precinct approached Saipov and shot him in the abdomen, police said. He has been taken to a hospital, but officials did not discuss his condition or location. The weapons he was brandishing turned out to be a pellet gun and a paintball gun, police said.
Rabbi Chaim Zaklos was picking up about half a dozen children from school to escort them to Hebrew school nearby when he encountered the scene. Police were pushing people away, and he could see abandoned bikes and what appeared to be uprooted trees nearby. “It was obvious something drastic was happening, so I just wanted to get the kids someplace safe,” said Zaklos, 35.
“This is a very painful day in our city,’’ New York City Mayor Bill de Blasio (D) said. “Based on the information we have at this moment, this was an act of terror, a particularly cowardly act of terror aimed at innocent civilians.”
Saipov moved to the United States from Uzbekistan about six years ago, said Dilnoza Abdusamatova, 24, who said Saipov stayed with her family in Cincinnati for his first two weeks in the country because their fathers were friends. Some officials said he arrived in 2010.
Abdusamatova said Saipov then moved to Florida to start a trucking company. Her family members think he got married about a year after arriving in the United States and may now have two children. Around that time, she said, he cut off contact with them.
“He stopped talking to us when he got married,” Abdusamatova said.
Saipov had lived in an apartment complex, Heritage at Tampa, near the Hillsborough River. On Tuesday evening, two plainclothes investigators were seen departing the community, having interviewed several residents and others in the surrounding neighborhood. The investigators declined to answer any questions.
“Four FBI agents came and told me he used to live here,” said Venessa Jones, who said she lives in an apartment above the one Saipov rented. Neighbors at the complex said they didn’t know Saipov.
Officials said they had no information to suggest that the attacker had any accomplices or that there was a further threat to the city.
Nevertheless, they said, extra police would be posted around the city as a precaution, particularly along the route of the Halloween Parade, a long-standing tradition in Manhattan’s Greenwich Village that attracts big crowds. Officials said sand trucks, police vehicles and other equipment would be used to deter any vehicle attacks at the parade.
The investigation is being led by the FBI with the assistance of the New York Police Department.
“We have recently seen attacks like this one throughout the world,’’ said acting homeland security secretary Elaine Duke. “DHS and its law enforcement partners remain vigilant and committed to safeguarding the American people.’’
Hours after the attack sent New Yorkers running for their lives, hundreds of cheerful Halloween revelers began lining up early to see the annual parade.
Sarah Butler, 24, said she had not heard much about the suspected terrorist attack and felt safe enough with the heavy police presence. “This is my first Halloween here,” said Butler, a film student. “It’s sad. I hope everyone is okay, but we shouldn’t let this ruin everything.”
Ivo Araujo, 72, and a group of about a dozen drummers hammered out a rhythm along Varick Street as they prepared for the parade to begin.
“We heard about it, but what can you do?” he said when asked whether he and his group, Manhattan Samba, had any qualms about making their 27th appearance in the parade. “The cops are going to take care of us. Nothing is going to happen. It’s going to be great.”
Michael Walz, 40, was tapping a snare next to him. Walz lives in Rio de Janeiro as well as New York and said he was used to violent attacks, in part because he was in Barcelona during a vehicle attack earlier this year.
A few blocks from the parade, parents were starting to bring their children home from trick-or-treating. Among them were Marianne Aulie, 46, walking with her daughter and her pumpkin-costumed toddler strapped to her chest.
Aulie had some qualms about heading out after hearing news of the attack shortly before they left the house. She said she generally felt safe with all the police in the area but was still nervous.
She noted that such events are becoming common. “It was unexpected but expected,” she said. “We can’t let fear take us.”
As she spoke, a large truck turned a nearby corner. “When you see a big truck now, you, you know. . . .” She trailed off. A man who was with her pointed out that it was a police bomb squad truck. “Bomb squad!” her daughter chirped.
Barrett and Lowery reported from Washington. Philip Bump in New York, Jon Silman in Tampa, and Julie Tate, Ellen Nakashima, Jennifer Jenkins, Mark Berman and Rachel Siegel in Washington contributed to this report.
WASHINGTON — Executives from Facebook, Google and Twitter appeared on Capitol Hill for the first time on Tuesday to publicly acknowledge their role in Russia’s influence on the presidential campaign, but offered little more than promises to do better. Their reluctance frustrated lawmakers who sought stronger evidence that American elections will be protected from foreign powers.
The hearing, the first of three in two days for company executives, served as an initial public reckoning for the internet giants. They had emphasized their role as public squares for political discourse but are being forced to confront how they were used as tools for a broad Russian misinformation campaign.
Both Democrats and some Republicans on a Senate Judiciary subcommittee complained that the companies had waited nearly a year to publicly admit how many Americans were exposed to the Russian effort to spread propaganda during the 2016 campaign. Senators pushed for harsher remedies, including regulations on their advertising practices akin to rules for political advertising on television.
The podcast that makes sense of the most delirious stretch of the 2016 campaign.
“Why has it taken Facebook 11 months to come forward and help us understand the scope of this problem, see it clearly for the problem it is and begin to work in a responsible legislative way to address it?” asked Senator Chris Coons, Democrat of Delaware.
The most pointed exchanges were aimed at Facebook, which admitted on Monday before the hearings that more than 126 million users potentially saw inflammatory political ads purchased by a Kremlin-linked company, the Internet Research Agency. Facebook has drawn particular ire from lawmakers for its early brushoff of fake news and foreign interference on its site, which its chief executive, Mark Zuckerberg, dismissed as a “crazy idea” just after the election.
Since then, the company has scrambled to appease lawmakers by promising to hire more than 1,000 people to manually review political ad purchases and to make the funding of those ads public.
“The foreign interference we saw was reprehensible,” Colin Stretch, Facebook’s general counsel, told senators.
The companies also acknowledged they were struggling to keep up with the threat of foreign interference.
“The abuse of our platform to attempt state-sponsored manipulation of elections is a new challenge for us — and one that we are determined to meet,” Twitter’s acting general counsel, Sean Edgett, said.
At the heart of the companies’ problems are business models that reward viral content — which can include misinformation — and an enormous advertising business that is automated and unable to easily spot ads purchased by foreign governments.
In a sign of the shifting political winds for tech giants, Republicans, who have been more restrained in their criticism of the companies, were more skeptical on Tuesday. In one contentious exchange, Senator John Kennedy, Republican of Louisiana, pressed Mr. Stretch on whether Facebook could possibly police all of its advertisers.
“I’m trying to get us down from La-La Land here,” Mr. Kennedy said. “The truth of the matter is, you have five million advertisers that change every month. Every minute. Probably every second. You don’t have the ability to know who every one of those advertisers is, do you?”
Mr. Stretch acknowledged that Facebook could not track all of those advertisers.
Senator Lindsey Graham, Republican of South Carolina, the chairman of the crime and terrorism subcommittee that held the hearing, said the risk went beyond Russia to other American adversaries. Talking to reporters afterward, he alluded to potential regulation of political advertising online.
“It’s Russia today; it could be Iran and North Korea tomorrow,” he said. “We need to do is sit down and find ways to bring some of the controls we have on over-the-air broadcast to social media to protect the consumer.”
Facebook, Twitter and Google have not publicly opposed a bipartisan proposal to require reports on who funds political ads online, similar to rules for broadcast television. In private, their lobbyists have praised voluntary efforts to disclose political ad funding and have resisted many aspects of the bill.
Senator Amy Klobuchar, Democrat of Minnesota, said the legislation was essential before the midterm elections in 2018.
“Our midterms are 370 days away, and we don’t have time to mess around with dialogue anymore,” Ms. Klobuchar said in an interview after the hearing. Ms. Klobuchar introduced the bill with Senator Mark Warner, Democrat of Virginia, and Senator John McCain, Republican of Arizona.
During the hearing, some Republicans also sought to play down the Russian effort to tip the election in favor of President Trump, stressing incorrectly that the Kremlin’s agents did not favor a particular presidential candidate in last year’s election.
“Russia does not have loyalty to a political party in the United States,” said Senator Charles E. Grassley, the Republican chairman of the Judiciary Committee. “Their goal is to divide us and discredit our democracy.”
That assertion was at odds with the conclusion of American intelligence agencies that President Vladimir V. Putin of Russia tried to sway the election in favor of Mr. Trump, going beyond just posting disruptive content on social media. Russian operatives also hacked Democratic email accounts and released messages embarrassing to Hillary Clinton’s campaign.
Mr. Graham asked Mr. Stretch, Facebook’s general counsel, to confirm that the pattern of activity Facebook saw from Russia was more focused on sowing chaos in the United States than in bolstering Mr. Trump’s candidacy.
“During the election, they were trying to create discord between Americans, most of it directed against Clinton,” Mr. Graham said, addressing Mr. Stretch. “After the election, you saw Russian-tied groups and organizations trying to undermine President Trump’s legitimacy. Is that what you saw on Facebook?”
Mr. Stretch agreed. But the question was narrowly tailored, apparently intended to distance the broader Russian interference from the backing of Mr. Trump.
Though the companies made promises to work with government officials, Mr. Stretch stopped short of agreeing to some suggestions.
In one heated exchange, Senator Al Franken, Democrat of Minnesota, asked him to reject political ad purchases in foreign currencies.
“How did Facebook, which prides itself on being able to process billions of data points and instantly transform them in the personal connections with its user, somehow not make the connection that electoral ads, paid for in rubles, were coming from Russia?” Mr. Franken said.
But Mr. Stretch hemmed, saying the rejection of a foreign currency to buy political ads would not solve the problem of foreign interference.
“The reason I’m hesitating on foreign currency is it’s relatively easy for bad actors to switch currencies,” Mr. Stretch said. “So it’s a signal, but not enough.”
That response failed to satisfy Mr. Franken, who interrupted with exasperation.
“My goal is for you to think through this stuff a little bit better,” Mr. Franken said, raising his voice.
This week, the companies admitted that the abuse of their platforms was much greater than previously acknowledged. In addition to Facebook’s admission, Google said that agents who were also from the Kremlin-linked Internet Research Agency uploaded more than 1,000 videos on its YouTube platform. Twitter said the Russian agency published more 131,000 messages on Twitter.
On Wednesday, the top lawyers for all three companies will appear before the House and Senate intelligence committees, which are conducting their own investigations into the Russian election meddling.
Tuesday’s hearing exposed a much deeper struggle for Facebook, which is trying to tread a delicate line as a technology platform while also fighting against hate speech, violence and misinformation on its site.
“I like that they are contrite, but these issues are existential they aren’t taking any structural changes,” said Tim Wu, a professor of law at Columbia University. “These are Band-Aids.”
President Trump on Tuesday belittled former foreign policy adviser George Papadopoulos, who pleaded guilty this week to lying to federal agents investigating Russia’s interference in the 2016 election, tweeting that “few people knew the young, low level volunteer named George, who has already proven to be a liar.”
But interviews and documents show that Papadopoulos was in regular contact with the Trump campaign’s most senior officials and held himself out as a Trump surrogate as he traveled the world to meet with foreign officials and reporters.
Papadopoulos sat at the elbow of one of Trump’s top campaign advisers, then-Sen. Jeff Sessions, during a dinner for campaign advisers weeks before the Republican National Convention, according to an individual who attended the meeting.
He met in London in September 2016 with a mid-level representative of the British Foreign Office, where he said he had contacts at the senior level of the Russian government.
And he conferred at one point with the foreign minister of Greece at a meeting in New York.
While some top campaign aides appeared to rebuff Papadopoulos’s persistent offers to broker a meeting with Russian President Vladimir Putin, there is no sign they told him directly to cease his activities or sought to end his affiliation with the campaign.
Emails included in court documents released Monday show that Papadopoulos repeatedly told Trump campaign officials about his contacts with people he believed were representing the Russian government.
The court documents do not answer a key question: whether Papadopoulos also told his superiors that he had met a London-based professor who claimed to know that the Russians had “dirt” on Democratic candidate Hillary Clinton, including thousands of her emails.
An FBI agent told the court in July that Papadopoulos lied in an interview with federal agents, saying he did not tell anyone on the campaign about the “dirt” because he thought the professor was a “nothing.”
At 29, Papadopoulos had scant experience that qualified him to advise a presidential candidate. He had entered the Trump campaign after a six-week stint working for the campaign of Trump’s rival for the Republican nomination, neurosurgeon Ben Carson.
Carson’s campaign manager, Barry Bennett, recalled that Papadopoulos was hired after sending him an unsolicited message via LinkedIn seeking a job.
At the time, Carson’s campaign was desperate to show it had policy experts advising his campaign, given that most leading Republican foreign policy thinkers had been snapped up by other candidates.
Bennett said his only vetting was to ask a friend at the Washington-based Hudson Institute, where Papadopoulos’s résumé indicated he had worked as a researcher, whether Papadopoulos was “an okay guy.”
“I wasn’t looking for something stellar,” Bennett said. “I wanted to make sure he was okay.”
For six weeks of work, Bennett said, Papadopoulos was paid $8,500, before he was let go from the campaign at the end of January 2016 as it shed staff.
By March 2016, Trump’s campaign, like Carson’s before it, was eagerly searching for foreign policy expertise. As Trump rose in the polls and won Republican primaries, the former reality TV host was under pressure to announce a group of advisers with whom he was consulting on foreign policy issues.
The scrutiny intensified early that month after 70 conservative national security experts signed an open letter opposing Trump’s candidacy. In mid-March, Trump was asked on the MSNBC show “Morning Joe” to name people with whom he spoke about foreign affairs.
“I’m speaking with myself, number one, because I have a very good brain,” Trump responded, prompting more calls for a list of formal advisers.
To come up with names, the campaign turned to Sam Clovis, a former Iowa radio host who served as national campaign co-chairman, an attorney for Clovis confirmed Tuesday in a statement.
But the statement did not address how Papadopoulos ended up on the list. Bennett said he was not consulted and would not have recommended his former employee if he had been asked because he found him unimpressive.
On March 21, Trump included Papadopoulos among five men he announced were advising him on matters of national security in a meeting with The Washington Post editorial board. “An energy and oil consultant. Excellent guy,” Trump said.
If Trump or his team had undertaken even a cursory vetting of Papadopoulos, they would have found that much of his already-slim résumé was either exaggerated or false.
While he claimed to have served for several years as a fellow at the Hudson Institute, officials there said he had been an unpaid intern and a researcher under contract to several fellows who were writing a book.
Although he claimed to be “U.S. Representative at the 2012 Geneva International Model United Nations,” officials at that organization said they had no record of him.
Papadopoulos said he had delivered the “keynote address” at a leading American-Greek organization in 2008 — while a student at DePaul University. But records from the gathering indicate he merely participated in a youth panel with other participants. The keynote was delivered by 1988 Democratic presidential candidate Michael Dukakis.
Though Papadopoulos’s exaggerated résumé issues quickly became public, he remained a part of the Trump advisory panel and soon began urging campaign aides to let him set up a meeting between Trump and Russian officials.
Court documents show he raised the idea at a March 31 meeting of the group attended by both Trump and Sessions, who had endorsed Trump’s campaign, telling the group that “he had connections that could help arrange a meeting between then-candidate Trump and President [Vladimir] Putin.”
He also began appearing in the foreign press. While visiting Israel the next month, he told a group of researchers that Trump saw Putin as “a responsible actor and potential partner,” according to a column in the Jerusalem Post.
In May, he told the Telegraph of London that Prime Minister David Cameron should apologize to Trump for calling the candidate “divisive, stupid and wrong.” Cameron’s comments had come after Trump announced that he supported a ban on Muslims entering the United States.
Papadopoulos’s comments were big news in Britain — and the campaign took notice.
J.D. Gordon, a former Pentagon spokesman and Trump national security adviser, said campaign officials were displeased, and Papadopoulos was counseled that he should clear future media appearances with campaign staff and keep a low profile.
“I was surprised to learn what George Papadopoulos was up to during the campaign,” he said Tuesday in a text message. “He obviously went to great lengths to go around me and Sen. Sessions.”
And yet, Papadopoulos continued to be invited to campaign events. In late June or early July, he attended a dinner at the Capitol Hill Club along with several other national security advisers for the Trump campaign.
Another person who was at the meeting said Sessions also attended; Papadopoulos was seated to Sessions’s left.
A spokeswoman for Sessions declined to comment.
Media appearances by Papadopoulos continued.
In September, he spoke extensively to Interfax, telling the Russian news agency that Trump “has been open about his willingness to usher in a new chapter” in U.S.-Russia relations, depending on “Russia acting as a responsible stake holder in the international system.” He also questioned the effectiveness of U.S. sanctions on Russia.
By that time, WikiLeaks had released emails hacked from the Democratic National Committee that were widely suspected to have been stolen at the direction of the Russian government. Trump’s warm rhetoric toward Putin had become a controversial topic on the campaign trail.
Court documents show that Papadopoulos forwarded a copy of the Interfax article to a Russian woman with whom he had been corresponding during the campaign.
British sources said it was around that time that he approached British government officials to say he was traveling to London and asked to be given a meeting with senior government ministers. Instead, he was offered a session with a mid-level official at the Foreign Office in London.
During the meeting, Papadopoulos made a comment indicating he had contacts at the senior level of the Russian government, British sourcessaid. British officials quickly concluded he was not a major or knowledgeable player in the Trump orbit and did not pursue the issue or continue contact.
A spokesman for the Greek Embassy said he met with that nation’s foreign minister in New York. Spokesman Efthymios Aravantinos said the conversation was conducted as part of a routine effort that the embassy makes to reach out to Greek Americans “hoping they have a sentimental attachment to Greece and that we can connect.”
It is not clear how much the campaign knew about Papadopoulos’s activities. But he continued through these months to have contact with other Trump officials.
In September, Papadopoulos emailed another Trump aide, Boris Epshteyn, and told him he planned to be in New York and hoped to set up meetings around the U.N. General Assembly meeting.
The email was described to The Washington Post in August of this year and is among 20,000 pages of documents that the Trump campaign has turned over to the White House, Congressional committees and defense attorneys.
Papadopoulos wrote that he wanted to connect Epshteyn with a friend, Sergei Millian of the Russian American Chamber of Commerce, the emails said.
Millian would later be identified as a major source for the author of a dossier that included unsubstantiated salacious allegations about Trump’s activities in Russia, a claim Millian has denied.
Epshteyn said he never met Millian and declined to comment further. Asked in August to describe his relationship with Papadopoulos, Millian responded by email, “I can meet and talk to any person. . . . It’s none of your business.”
Millian did not respond to a request for comment Tuesday.
Papadopoulos continued to hold himself out as a Trump adviser, even after the November election.
Two days after Trump’s inauguration in January, he met in Washington with a group of Israelis headed by Yossi Dagan, a leader of the West Bank settler movement that prepared a video of the session to be shown at home.
“We had an excellent meeting with Yossi and we hope that the people of Judea and Samaria” — the name used by the Israeli right for the West Bank — “will have a great 2017,” Papadopoulos said, according to the video. “We are looking forward to ushering in a new relationship with all of Israel.”
According to an account in the Jerusalem Post, the settler leaders had been invited to attend the inauguration and meet with “senators, congressmen and members of the President’s team.” Dagan, reached by telephone Tuesday in Israel, declined to comment on the visit or who had arranged the meeting with Papadopoulos.
While the president now seems to have left Papadopoulos behind, Papadopoulos has continued to highlight the tie. On LinkedIn, he indicates he was a Trump adviser through January 2017 and includes the experience as the first line of his description about himself.
“President Trump recommendation about me: ‘George is an oil and gas consultant; excellent guy,’ ” Papadopoulos wrote.
Dan Balz, Sari Horwitz and Devlin Barrett in Washington and Ruth Eglash in Jerusalem contributed to this report.
A driver plowed a pickup truck down a crowded bike path along the Hudson River in Manhattan on Tuesday, killing eight people and injuring 11 before being shot by a police officer in what officials are calling the deadliest terrorist attack on New York City since Sept. 11, 2001.
The rampage ended when the motorist — whom the police identified as Sayfullo Saipov, 29 — smashed into a school bus, jumped out of his truck and ran up and down the highway waving a pellet gun and paintball gun and shouting “Allahu akbar,” Arabic for “God is great,” before he was shot in the abdomen by the officer. He remained in critical condition on Tuesday evening.
Mayor Bill de Blasio declared the rampage a terrorist attack and federal law enforcement authorities were leading the investigation. Investigators discovered handwritten notes in Arabic near the truck that indicated allegiance to the Islamic State, two law enforcement officials said. But investigators had not uncovered evidence of any direct or enabling ties between Mr. Saipov and ISIS and were treating the episode as a case of an “inspired” attacker, two counterterrorism officials said.
Mr. de Blasio said at a news conference, “Based on information we have at this moment, this was an act of terror, and a particularly cowardly act of terror aimed at innocent civilians.”
Five of the people killed were Argentine tourists who traveled to New York for a 30-year high school reunion celebration, said a senior official in Santa Fe Province, where they were from. The Argentine authorities said they were Hernán Mendoza, Diego Angelini, Alejandro Pagnucco, Ariel Erlij and Hernán Ferruchi. Martín Ludovico Marro, a sixth member of the group, was wounded. Belgian officials said one of those killed and three of the injured were from Belgium.
Mr. Saipov came to the United States from Uzbekistan in 2010, and had a green card that allowed permanent legal residence. He had apparently lived in Paterson, N.J., and Tampa, Fla. An official said he rented the truck from a Home Depot in New Jersey.
The truck came crashing to a stop near the corner of Chambers and West Streets by Stuyvesant High School. Sirus Minovi, 14, a freshman there who was hanging out with friends, said people scattered.
“We heard people screaming, ‘gun’ ‘shooter’ and ‘run away,’” Mr. Minovi said. “We thought it was a Halloween prank.”
He realized it was not a joke when he saw the man staggering through the intersection, waving guns and screaming words he could not make out. A passer-by approached the attacker, apparently trying to calm him, Mr. Minovi said, until the man realized the attacker had a gun. The man “put his hands up and was backing away,” Mr. Minovi said.
Almost immediately, as investigators began to look into Mr. Saipov’s history, it became clear that he had been on the radar of federal authorities. Three officials said he had come to the federal authorities’ attention as a result of an unrelated investigation, but it was not clear whether that was because he was a friend, an associate or a family member of someone under scrutiny or because he himself had been the focus of an investigation.
Over the last two years, a terrorism investigation by the F.B.I., the Department of Homeland Security, the New York Police Department and federal prosecutors in Brooklyn resulted in charges against five men from Uzbekistan and one from Kazakhstan of providing material support to ISIS. Several of the men have pleaded guilty. It is unclear whether Mr. Saipov was connected with that investigation.
Martin Feely, a spokesman for the New York F.B.I. office, declined to comment on whether Mr. Saipov was known to the bureau.
F.B.I. agents were expected to search Mr. Saipov’s home in Paterson, N.J., and his car on Tuesday night, a law enforcement official said. A phone, which was recovered at the scene of the attack, also would be searched, another official said.
The attack unfolded as nearby schools were letting out on a Halloween afternoon. It ended five blocks north of the World Trade Center. The driver left a roughly mile-long crime scene: a tree-lined bike path strewn with bodies, mangled bicycles and bicycle parts, from wheels twisted like pretzels to a dislodged seat.
Mr. Saipov, a slim, bearded man, was seen in videos running through traffic after the attack with a paintball gun in one hand and a pellet gun in the other. Six people died at the scene and two others died at a hospital, officials said. The authorities credited the officer who shot him with saving lives.
“He was Johnny-on-the-spot and he takes the guy down,” a city official said.
Coming five months after a car rammed into pedestrians in Times Square, killing one, Tuesday’s attack again highlighted the danger of a vehicle attack on busy city streets. The Times Square attack was not an act of terrorism. But both events brought to mind the terrorist attack last year in Nice, France, in which a cargo truck killed scores of people celebrating Bastille Day.
The episodes also evoked calls from terrorist magazines, including in an edition of Rumiyah, a magazine used by ISIS, for attackers to mow down pedestrians with trucks, continue the attacks with a knife or a gun and claim responsibility by shouting or leaving leaflets.
Students in Halloween costumes streamed out of nearby schools after lockdowns were lifted and huddled with parents. Their faces, once painted for the holiday, were streaked with tears.
Emily, 12, a seventh-grader at I.S. 289 whose father asked that her last name not be used, had been walking on her usual route home when other students turned and ran in the other direction.
“All the kids were screaming, ‘Run!’, ‘Gun!’ ‘Run inside,’” she said, still wearing cat ears. She said mothers pushing strollers and children in costumes ran in a herd back toward the school.
President Trump responded to the attack on Twitter: “In NYC, looks like another attack by a very sick and deranged person. Law enforcement is following this closely. NOT IN THE U.S.A.!”
Gov. Andrew M. Cuomo cautioned at a news conference, “There’s no evidence that suggests a wider plot or a wider scheme.” In the aftermath, city and state law enforcement agencies increased security at high-profile locations.
Terrorism analysts noted that on Monday a French pro-ISIS media unit, known as the Centre Mediatique An-Nur, put out a specific threat for Halloween, mentioning the date on a banner spread on the encrypted app Telegram and on ISIS-affiliated Twitter accounts.
Mr. Saipov wove a deadly path on a stretch usually bustling with commuters, runners and cyclists, drawn by the downtown offices nearby or the shimmering river.
He turned onto the bike path alongside the West Side Highway at Houston Street just after 3 p.m. and sped south, striking numerous pedestrians and cyclists, many of them in the back, the authorities said. People scattered and dived to the asphalt.
The truck, labeled with a sign saying, “Rent me starting at $19,” rammed into the bus near Chambers Street. The bus serves two schools in Lower Manhattan and transports students with special needs. Two adults and two children on the bus were injured, the authorities said.
Reporting was contributed by Rukmini Callimachi, Jim Dwyer, Luis A. Ferré-Sadurní, J. David Goodman, Adam Goldman, Alexandra S. Levine, Daniel Politi and Eric Schmitt.
Rented truck used
CNN’s Jessica Schneider, Shimon Prokupecz, David Shortell, Steve Almasy, Karen Smith and Intisar Seraaj contributed to this report.
CNN’s Jessica Schneider, Shimon Prokupecz, Steve Almasy and Paul Murphy contributed to this report.
Joseph Serna is a Metro reporter who has been with the Los Angeles Times since 2012. He previously worked for papers in Orange County and Signal Hill, a 2.2-square-mile city surrounded by Long Beach. He was part of the team that won the Pulitzer Prize for Breaking News for coverage of the 2015 San Bernardino terrorist attack and is a graduate of California’s community college and Cal State systems. He’s also a notoriously picky eater.
CNN’s Jessica Schneider and Shimon Prokupecz contributed to this report.
Lawyers from Facebook, Google and Twitter are testifying on Capitol Hill Tuesday afternoon amid mounting political pressure to fully investigate Russian efforts to influence the 2016 U.S. presidential campaign and reveal publicly what they find.
It is a rare moment in the political spotlight for companies that, despite large lobbying teams in Washington, generally seek to avoid such public and potentially unpredictable confrontations. A growing number of lawmakers have expressed concern in recent weeks about the Russian online influence campaign and are vowing both to expose what happened and work to prevent a recurrence, through legislation if necessary.
Tuesday’s hearing by a Senate judiciary subcommittee comes a day after the prepared testimonies of Facebook and Twitter revealed that the reach of the Russian-connected disinformation campaign on their platforms was much larger than initially reported.
As many as 126 million Facebook users may have seen content produced and circulated by Russian operatives. Twitter said it had discovered that 2,752 accounts controlled by Russians, and more than 36,000 Russian bots tweeted 1.4 million times during the election. And Google disclosed for the first time that it had found 1,108 videos with 43 hours of content related to the Russian effort on YouTube. It also found $4,700 worth of Russian search and display ads.
Sen. Lindsey Graham (R-S.C.) opened the hearing by describing the dangers posed by the ability of terrorists to recruit followers over social media and foreign governments to meddle in American democracy.
“This is the national security challenge of the 21st Century,” Graham said.
But some senators pushed the tech companies to explain more about what their services can and can’t do — and what capabilities they have to prevent abuse. Sen. John Kennedy (R-La.) challenged Facebook’s General Counsel Colin Stretch with a series of pointed questions. “I’m trying to get us down from La La land here,” Kennedy said. “You have 5 million advertisers that change every year, every month, probably every second… You do not have the ability to know about every one of those advertisers, do you?”
When Stretch acknowledged that advertisers likely can obscure their identities, Kennedy interrupted him to ask pointedly, “Do you have a profile on me?” Then he asked if Facebook knew the movies that his fellow senator Graham liked, the bars he visited, who his friends were?
Stretch replied that Facebook has systems to prevent such invasions of privacy. “The answer is absolutely not… We have designed our system to avoid exactly that.”
After Kennedy sharply reminded Stretch that he was under oath, Kennedy turned his attention to Google lawyer Richard Salgado. The senator demanded to know whether the company was essentially a newspaper, rather than merely a neutral platform, given its role in distributing news reports worldwide. The issue has important consequences because, under federal law, technology platforms to not have the same legal responsibility for material they carry as traditional news sources that employs journalists.
“We are not a newspaper. We are a platform that shares information,” replied Salgado, Google’s director of law enforcement and information security. “This is a platform from which news can be read from many sources.”
Sen. Al Franken (D-Minn.) also took aim at Facebook, blasting the company for failing to discover the Russian online influence campaign sooner, especially given that many of the ads were paid for in rubles, the Russian currency. “American political ads and Russian money, rubles: How could you not connect those two dots!”
Stretch replied, “In hindsight we should have had a broader lens. There were signals we missed.”
Franken also demanded to know if Facebook would refuse American political ads in the future paid for in rubles or the North Korean currency, the won. Stretch said the company was going to seek to stop political manipulation by foreign actors, but the type of payment is not the most important factor.
“It’s relatively easy to change currencies,” he said.
The most important unanswered question going into the hearing, outside experts said, is whether the tech companies have evidence that might substantiate allegations that the Russians colluded with Donald Trump’s political campaign, which made Facebook in particular a focus of its election efforts in 2016. Trump and his campaign officials have repeatedly denied allegations of collusion, but questions about the role played by Russia are at the heart of investigations by Capitol Hill and Special Counsel Robert S. Mueller III, whose first round of charges against Trump campaign figures were unsealed Monday.
Sen. Charles Grassley (R-Iowa) said that his staff’s review of the 3,000 Russian-bought ads on Facebook suggests that most sought to sow discord around sensitive social issues, not try to convince Americans to vote for either Trump or Democrat Hillary Clinton. “Russia does not have loyalty to a political party in the United States. The goal is to discredit our democracy and divide us,” Grassley said.
Tuesday’s hearing offers lawmakers a direct and highly public opportunity to question tech company officials about how their platforms were manipulated, what they did in response, and what they plan to do to thwart similar efforts in the future. None of the companies are sending their top internal security researchers to the hearing, opting instead to send senior company lawyers. Also testifying will be Clinton Watts, a former FBI agent and disinformation expert from the Foreign Policy Research Institute, and Michael S. Smith III, a terrorism analyst.
“We are trying in the Subcommittee to lay out the Kremlin playbook on election interference generally, since this is something that they do in a great number of countries,” said Sen. Sheldon Whitehouse (R.I.), the top Democrat on the Judiciary panel hosting the first of the three hearings, in an interview on Monday. “And we are looking to delve into which elements of the the Kremlin playbook were deployed in the United States specifically.”
Testifying at Tuesday’s hearing are Stretch, Salgado and Twitter’s acting general counsel Sean Edgett.
In his opening remarks, Stretch said, “The foreign interference we saw is reprehensible. That foreign actors, hiding behind safe accounts, abused our platform and other Internet services to try to sow division and discord — and to try to undermine the election — is an assault on democracy that is directly contrary to our values and violates everything Facebook stands for.”
Google’s Salgado said that while the company has found relatively small amounts of Russian manipulation on its services, “We understand that any misuse of our platforms for this purpose can be very serious.”
He also said the company would create a publicly accessible database of all election ads purchased on Google’s ad platforms and on YouTube. The company will also publish a transparency reports for election ads which will identify the purchasers and how much money was spent.
The hearing, as well as Wednesday’s hearings before the Senate and House Intelligence committees, comes amid pushes by Sens. Mark Warner (D-Va.), Amy Klobuchar (D-Minn.) and John McCain (R-Ariz.) to pass new legislation forcing tech companies to disclose information about political ads sold and distributed on their networks. Warner, the top Democrat on the Senate Intelligence Committee, said that colleagues on the committee chose to wait until they heard testimony of the tech companies before they signaled their interest.
The bill, dubbed the “Honest Ads Act,” would require digital platforms with more than 50 million monthly viewers to create a public database of political ads purchased by a person or group who spends more than $500. The public file would include the ad, a description of the targeted audience, the number of views it generated, the date and time it ran, its price and contact information for the purchaser.
During the hearings, Sen. Klobuchar pointedly asked each company executive whether they would support the bill. None of them said yes.
At one point, Facebook was asked directly whether its service could affect the outcome of the election.
Sen. Mazie Hirono of Hawaii asked Facebook’s Stretch if he can say definitively that Russian efforts did not influence the outcome of the election. When Stretch said no, she asked again, citing the closeness of the presidential contest, “Can you say that it didn’t have an impact on the election?
“Senator, we’re not well positioned to judge why any one person or an entire electorate voted as it did,” he said.
Shortly after the election, in November, Mark Zuckerberg dismissed the idea that fake news on Facebook could have impacted that election as “a crazy idea.”
But even as lawmakers move to prevent future manipulation, they will use the hearings to probe how foreign actors were able to disseminate propaganda. “Russia will be the star of the hearings,” said Darrell West, the director of the Brookings Center for Technology Innovation.
Beyond providing the public with a fuller picture of election meddling, experts said the hearings symbolize a broader recognition of the significance massive tech platforms hold in American discourse and politics.
“It’s hard to reconcile the tens of billions of dollars of profit they make with the lack of attention they’ve had with something that could possibly affect our democracy,” said Jason Kint, chief executive of Digital Content Next, a trade organization that represents digital media companies. “The questioning is deeply uncomfortable for them because it gets to the root of their business model, which few people really understand.”