Update 3.50pm: The driver in New York's deadly vehicle bombing had been planning it for weeks and did it "in the name of Isis", a New York police department official has said.
Deputy Commissioner John Miller made the remarks at a briefing on Wednesday by city, state and US federal officials.
He said there were "multiple knives" in addition to imitation guns displayed by the attacker, who was wounded by a police officer.
Hundreds of detectives worked through the night following the Tuesday attack.
Among other things, they've been "meticulously" collecting security video along the road that the suspect used before mowing down people on a bike path next to the World Trade Centre, killing eight people.
Sayfullo Saipov was argumentative, seemed to harbour radical views and saw his work life spiralling down, a fellow lorry driver said.
Mirrakhmat Muminov said Saipov lived in Ohio for a few years.
He said he knew Saipov because they were both Uzbek lorry drivers.
Mr Muminov said Saipov lost his insurance on his vehicle because of a few traffic tickets and that companies stopped hiring him, so he left for New Jersey.
Mr Muminov said he heard from Saipov's friends that the suspect's lorry engine blew up a few months ago in New Jersey.
He said that "probably hurt him more than anything".
Mr Muminov also said Mr Saipov was "not happy with his life" and would get into arguments with his friends and family.
Authorities have said Saipov left a handwritten note referring to the Islamic State group.
Mr Muminov said Saipov never spoke about the group, but he could tell Saipov held more radical views.
Update 2.20pm: Trump calls for crackdown on 'Diversity Visa Lottery' as attacker gained entry on programme
President Donald Trump has called for "merit based immigration" following the deadly vehicle attack in New York City that killed eight people and injured 11.
Mr Trump said on Twitter on Wednesday that the driver in Tuesday's attack "came into our country through what is called the 'Diversity Visa Lottery Program', a Chuck Schumer beauty."
Mr Schumer is a senior Democrat senator.
Officials said the attacker is an immigrant from Uzbekistan who came to the US legally in 2010.
They have not said whether he came in through the diversity immigrant visa programme, which covers immigrants from countries with low rates of immigration to the US.
Mr Trump tweeted: "We are fighting hard for Merit Based immigration, no more Democrat Lottery Systems. We must get MUCH tougher (and smarter)."
Update: 10.10am: Uzbekistan president offers support to Trump following NY terror attack
Uzbekistan's president has offered his support to Donald Trump following the terror attack in New York.
A suspect from the country, Sayfullo Saipov is thought to have driven a truck which ploughed into pedestrians on a cycle path, killing eight people.
Update 9.52am: A note pledging allegiance to Islamic State found in terror truck
It is being reported that a note pledging allegiance to Islamic State has been found in a truck which crashed into people in New York.
8 people are dead and at least ten are injured after a man drove a truck into people on a cycle path in Manhattan.
A 29-year-old from Uzbekistan has been arrested and is having surgery after being shot by police.
Update 9.50am: Five friends celebrating reunion among eight killed
Five friends from Argentina celebrating the 30th anniversary of their graduation were among those killed when a rental truck was driven into pedestrians and cyclists on a bike path in New York.
The men were reportedly part of a group of 10 friends exploring Manhattan on bicycles when the truck struck in Lower Manhattan on Tuesday.
In response to the atrocity - the deadliest terror attack to strike New York since September 11 - president Donald Trump ordered the security services to "step up" vetting procedures.
Eight people were killed and at least 11 others injured after a man drove the rented Home Depot truck on to the path on West Street at around 3pm local time (7pm GMT).
The driver, who has been identified by law enforcement officials as Sayfullo Saipov, 29, from Uzbekistan, was shot by police after jumping out of the vehicle with what turned out to be two fake guns.
He was taken to hospital and is in police custody.
Officers said his injuries are not life-threatening.
Hours after the attack, the names of the first victims emerged as Argentina's foreign ministry said Hernan Diego Mendoza, Diego Enrique Angelini, Alejandro Damian Pagnucco, Ariel Erlij and Hernan Ferruchi had died.
The group were marking three decades since their graduation from Polytechnic College in the city of Rosario in central Argentina.
A sixth Argentinian man with the group, Martin Ludovico Marro, was taken to the Presbyterian hospital in Manhattan.
A Belgian national was also among the dead, the country's deputy prime minister said.
Last night, police investigating the rampage were seen surrounding a white Toyota minivan with Florida number plates in the car park of Home Depot in Passaic, New Jersey.
Saipov had allegedly rented the pick-up truck an hour before the rampage from the state before unleashing terror on the streets of New York.
He reportedly shouted "Allahu akbar".
New York mayor Bill de Blasio described the attack as "a particularly cowardly act of terror" that was "aimed at innocent civilians going about their daily lives".
The 29-year-old suspect had been working as an Uber driver after passing a background check, according to a spokeswoman for the app.
In a statement, the firm added: "We are horrified by this senseless act of violence. Our hearts are with the victims and their families. We have reached out to law enforcement to provide our full assistance."
President Donald Trump praised the actions of the first responders and said on Twitter that he had ordered the Department of Homeland Security to step up its already "extreme vetting" programme, adding: "Being politically correct is fine, but not for this!"
A number of other officials in both the US and Europe offered condolences on social media.
Argentina's president Mauricio Macri tweeted: "Profoundly moved by the tragic deaths this afternoon in NY. We are at the disposal of the families of the Argentinian victims."
Foreign minister Jorge Faurie said that his heart was with the family and friends of those who had died "at this moment of deep and inexplicable pain".
New York mayor Bill de Blasio described the attack as "a particularly cowardly act of terror" while governor Andrew Cuomo said it was a "lone wolf" attack, and there was no evidence it was part of a wider plot.
The US president also tweeted: "We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!"
The terrorist group has not claimed responsibility for the attack.
Earlier: Eight dead as truck careers down New York Cycle path in terror attack
A man in a rented van mowed down cyclists and pedestrians in New York killing eight people in what the city's mayor called "a particularly cowardly act of terror".
He careered down a popular cycle path a few streets from the World Trade Centre memorial injuring at least 11 people.
The 29-year-old driver, named by authorities as Sayfullo Saipov, was shot in the stomach by police and arrested after jumping out of the van with what turned out to be a fake gun in each hand and shouting "Allahu Akbar!"
The suspect, originally from Uzbekistan, has a Florida driving licence but may have been living in New Jersey.
Uber confirmed that Saipov was one if its drivers, and the company said he passed a background check and had been actively driving on the platform for more than six months.
He has since been banned from the Uber app.
"We are horrified by this senseless act of violence," the company said in a statement. "Our hearts are with the victims and their families. We have reached out to law enforcement to provide our assistance."
The driver in Tuesday's attack barrelled along the bike path in a rented Home Depot truck for the equivalent of about 14 blocks, or around eight-tenths of a mile, before slamming into a small yellow school bus.
The mayhem and the burst of police gunfire set off panic in the neighbourhood and left the pavement strewn with mangled bicycles and bodies that were soon covered with sheets.
"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.
"This was an act of terror, and a particularly cowardly act of terror aimed at innocent civilians, aimed at people going about their lives who had no idea what was about to hit them," New York's mayor Bill de Blasio said.
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.
On Twitter, president Donald Trump called it "another attack by a very sick and deranged person" and declared, "NOT IN THE U.S.A.!"
My thoughts, condolences and prayers to the victims and families of the New York City terrorist attack. God and your country are with you!— Donald J. Trump (@realDonaldTrump) October 31, 2017
We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!— Donald J. Trump (@realDonaldTrump) October 31, 2017
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.!— Donald J. Trump (@realDonaldTrump) October 31, 2017
While police did not specifically blame the Islamic State group for the New York bloodshed, Mr Trump railed against the extremist group, tweeting, "We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!"
Records show Saipov was a commercial truck driver who formed a pair of businesses in Ohio after moving to the US.
The first business, Sayf Motors Inc., used the address of a family friend near Cincinnati with whom Saipov had stayed for a couple of weeks after his arrival in the country.
The second, Bright Auto LLC, used an address near Cleveland.
A trucking industry website listed Saipov at a Paterson, New Jersey, address that authorities were searching on Tuesday night.
Court records related to trucking-related infractions list Saipov with addresses in Paterson and the Cleveland suburbs.
The family friend with whom Saipov stayed in Ohio, Dilnoza Abdusamatova, told The Cincinnati Enquirer Saipov was "really calm" and worked hard.
"He always used to work," Ms Abdusamatova said. "He wouldn't go to parties or anything. He only used to come home and rest and leave and go back to work."
Police said Saipov rented the truck at about 2pm in New Jersey, entering the bike path about an hour later on West Street a few blocks from the new World Trade Centre, the site of the deadliest terror attack in US history.
The truck then turned at Chambers Street, hitting the school bus and injuring two adults and two children.