The Uzbek immigrant who killed eight people in New York's worst attack since September 11, 2001 was associated with the Islamic State jihadist group but became radicalised after moving to the United States, it emerged on Wednesday.
The driver, who moved to America in 2010, mowed down pedestrians and cyclists over a mile-long stretch of a bike path on Lower's Manhattan's West Side, as children and their parents prepared to celebrate Halloween on Tuesday afternoon.
Police shot the 29-year-old suspect, Sayfullo Saipov, in the abdomen after he crashed into a school bus and exited his pickup truck, brandishing paintball and pellet guns. He remains in custody but is expected to survive the shooting.
"He's a depraved coward is what he is, and he was associated with ISIS, and he was radicalised domestically," New York State Governor Andrew Cuomo told CNN.
The governor confirmed "a note that referenced ISIS" was found at the scene. US media said it was written in Arabic and pledged allegiance to the jihadist group. Saipov also reportedly shouted "Allahu Akbar".
"After he came to the United States is when he started to become informed about ISIS and radical Islamic tactics," Cuomo told CNN.
"We have no evidence yet of associations or a continuing plot or associated plots, and our only evidence to date is that this was an isolated incident that he himself performed."
Vehicle rammings have been a frequent tactic deployed by IS sympathisers in the West, including in Barcelona, London, Stockholm and in Nice, where a Tunisian suicide truck bomber killed 86 people on Bastille Day.
Busy life went on Wednesday, although New Yorkers confessed to feeling unnerved by an attack that brought back memories of 9/11 with a stepped up police presence across the city. The New York Stock Exchange observed a moment of silence.
"I am scared," said Megan Brosterman, a 38-year-old mother dropping off two children at school close to the scene.
"It does bring memories from 9/11. I worked in a building in this same neighbourhood in 9/11. I can't change my routine because of this," she said. "Life goes on."
Saipov reportedly moved to the United States in 2010, living in Florida and Ohio, before moving to Paterson, a former industrial hub in New Jersey about 20 miles (32 kilometres) northeast of New York, where he lived with his wife and two children.
He struck in broad daylight in the upscale neighbourhood of TriBeCa, close to schools and just blocks from the memorial to the 9/11 attacks, when Al-Qaeda hijackers killed more than 2,700 people in New York and brought down the Twin Towers.
Five of the eight killed were Argentines, part of a group visiting New York for a school reunion, the foreign ministry in Buenos Aires said. A Belgian woman on a trip with her mother and sister was also killed, Brussels said.
One Argentine, a German and three Belgians, were among the at least 11 wounded.
President Donald Trump, facing what appears to be the worst jihadist-inspired attack of his less than one year in office, denounced the culprit as "deranged" and announced a stepping-up of his "extreme vetting program" for foreign travelers.
He tweeted on Wednesday that the suspect had entered the United States via the green card lottery programme supported by opposition Democrats.
"We are fighting hard for Merit Based immigration, no more Democrat Lottery Systems. We must get MUCH tougher (and smarter)," Trump tweeted.
The announcement was met with criticism in New York, a Democrat-run state and city, which has for centuries been a key point of arrival for immigrants and prides itself on the diversity of its more than 8.5 million-strong population.
The New York Times
said the attacker had previously been on the radar of federal authorities, but it was not clear whether he himself had been the focus of an inquiry or whether he was linked to someone else under scrutiny.
In March 2015, two Uzbeks and a citizen of Kazakhstan living in New York were arrested on charges of supporting IS. One of them, who threatened former president Barack Obama, was sentenced to 15 years in prison last week.
Uzbekistan, a majority Muslim country that borders Afghanistan and formerly part of the Soviet Union, is a landlocked country racked with poverty, corruption and stifling authoritarian regime.
In less than a year, three other men with Uzbek links have been blamed for a deadly nightclub shooting in Istanbul, a Saint Petersburg metro bombing and a truck attack in Stockholm.
Uzbekistan's President Shavkat Mirziyoyev offered any help to US investigators. US officials said that Saipov had a string of traffic violations and that the truck had been rented in New Jersey.