The truck driver suspected of killing eight people when he ploughed through crowds on a New York cycle lane pledged allegiance to Isis in a note before the attack, officials have said.
The suspect, named as 29-year-old Uzbekistan national Sayfullo Saipov, injured at least 11 other people in the rampage near the World Trade Center memorial site on Tuesday afternoon.
He was shot by police in the abdomen after exiting the car with what turned out to be a fake gun in each hand and shouting “Allahu Akbar”.
Police found images of the Isis flag in his rented truck as well as handwritten notes pledging allegiance to the terrorist group, sources told the New York Post.
Suspect: Sayfullo Saipov (AP)
The note was reportedly hand-written in a foreign language, possibly Arabic. The contents are being investigated, but officials say the document supported the belief the act was terrorism.
Within hours of the incident, New York’s mayor Bill de Blasio called it a “particularly cowardly act of terror aimed at innocent civilians”.
New York terror attack – in pictures
New York’s governor, Andrew Cuomo called it a “lone wolf” attack and said there was no evidence to suggest it was part of a wider plot.
The city’s police commissioner, James O’Neil said the comments made by the suspect as he fled his truck – witnesses heard him say “Allahu Akbar” – led them to believe it was a terror incident.
Heavily armed police stand guard near the scene in Lower Manhattan (AP)
Meanwhile, Donald Trump had already linked the attack to Isis despite no claim of responsibility from the group itself.
“We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!” he wrote on Twitter.
He also described the attacker – who is expected to recover from the gunshot wound in hospital – as a “sick and deranged” person.
On Tuesday night the president said he had ordered the Department of Homeland Security “to step up our already Extreme Vetting Program” in the wake of the attack.
His extreme vetting policy on immigrants entails more stringent investigative measures intended to identify those who may sympathise with extremists or pose a national security risk.
It came as more details began to emerge about the suspect behind the worst terror attack seen in New York since 9/11.
Saipov was named by US media following the attack, with official sources confirming his identity later on. According to NBC, he has been living in the US since arriving in 2010.
One of his friends said Saipov was “very friendly” and had been living in New Jersey and working for Uber over the past year.
Kobiljon Matkarov, 37, told the New York Post: “He is very good guy, he is very friendly… he is like little brother… he look at me like big brother.
“My kids like him too, he is always playing with them. He is playing all the time.”
Saipov previously worked as a commercial truck driver and has a minor criminal record for traffic offences in Missouri and Pennsylvania, according to online records.
The incident began when the driver barrelled along a busy cycle path for nearly a mile before slamming into a small yellow school bus.
The mayhem and the burst of police gunfire set off panic in the area and left the pavement strewn with mangled bicycles and bodies that were soon covered with sheets.
New York terror attack: What we know so far
“I saw a lot of blood over there. A lot of people on the ground,” said Chen Yi, an Uber driver.
Eugene Duffy, a chef at a waterfront restaurant, said: “So many police came and they didn’t know what was happening. People were screaming. Females were screaming at the top of their lungs.”
Police closed off streets across the western edge of Manhattan along the Hudson River and officers rushed into the neighbourhood just as people were preparing for Halloween festivities, including the big annual parade through Greenwich Village.
Argentina’s foreign ministry has said “Argentine citizens died” in the New York cycle path terror attack, while a Belgian national was also thought to be among the victims.
Theresa May said she was “appalled” by the “cowardly attack” in a statement shared on social media.
“My thoughts are with all affected. Together we will defeat the evil of terrorism. UK stands with NYC,” the Prime Minister tweeted.
London mayor Sadiq Khan paid tribute to the victims and said “London stands in grief and solidarity with the great city of New York tonight.”
He denounced the “despicable and cowardly terrorist attack in Manhattan”.
He added: “My heart goes out to the victims and their families.
“New Yorkers are strong and resilient – I know they will not be cowed by this assault on the innocent, and on our shared values and way of life.”