Eight people were killed and more than a dozen injured in the attack
A man suspected of killing eight people and injuring at least ten more in a New York City truck attack left a note pledging allegiance to Islamic State, according to reports in the US.
The attacker has been named in media reports as 29-year-old Sayfullo Habibullaevic Saipov.
It is believed he drove 14 blocks before entering the cycle route and eventually crashing into a school bus and jumping from the rented truck with two replica guns.
He was then shot in the abdomen by police and is expected to survive after undergoing surgery.
The attack occurred at 3:05pm local time in Lower Manhattan.
According to witnesses he shouted "Allahu Akbar" - Arabic for "God is great" - during the attack.
New York Governor, Andrew Cuomo described the incident as a "lone wolf" attack and said there was no evidence suggesting it was part of a larger plot.
Six of the victims of the attack were confirmed dead at the scene. Two others were taken to hospital "in traumatic arrest" but died soon afterwards.
Of the eight people killed in the attack the majority are foreign nationals, with five belonging to the same group from the Argentine city of Rosario.
The friends were visiting New York as part of a 30th anniversary school reunion when they were killed, the country's foreign ministry revealed.
The party had rented bikes in the city and were reportedly on a cycling path in Lower Manhattan when they were mowed down.
Argentina's foreign ministry has named the victims as Hernan Diego Mendoza, Diego Enrique Angelini, Alejandro Damian Pagnucco, Ariel Erlij, and Hernan Ferruchi, from Rosario.
A sixth member of the group, all graduates of the Argentine city's Polytechnic College, Martin Ludovico Marro, was among the 11 people injured in the attack and is recovering in hospital.
Mr Erlij, a 48-year-old businessman and steel mill owner, paid for the costs of the trip for some of his friends so they could make the class of 1987 reunion in the Big Apple, according to media reports in Argentina.
A sixth victim, from Belgium, was announced by foreign minister Didier Reynders in the hours following the attack.
Accounts of the incident described a street littered with mangled bicycles and bodies that were quickly covered with sheets after the arrival of scores of police officers.
"I saw a lot of blood over there," Chen Yi, an Uber driver, told Associated Press. "A lot of people on the ground."
In a statement this morning, the Taoiseach Leo Varadkar expressed his condolences to the people of New York.
"This was a vicious and heartless attack on the people of New York - striking just a few blocks from the site of the 9/11 atrocity,” he said.
"Those who have been killed and injured were innocent victims going about their day, completely unaware of what was about to happen.
"I would like to express our solidarity with New Yorkers, who have faced considerable adversity in the past.
“Our thoughts and prayers are with the families and friends of the victims."
Authorities, speaking under anonymity, have revealed Saipov, who worked as a truck and Uber driver entered the US legally in 2010.
The Uzbekistan national had lived in Tampa, Florida, and New Jersey.
President Donald Trump responded to the incident with a series of tweets, first describing the attack as the work of a "sick and deranged person" and saying "we must not allow ISIS to return", before offering condolences to the victims.
He later tweeted: "I have just ordered Homeland Security to step up our already Extreme Vetting Program. Being politically correct is fine, but not for this!"
I have just ordered Homeland Security to step up our already Extreme Vetting Program. Being politically correct is fine, but not for this!— Donald J. Trump (@realDonaldTrump) November 1, 2017
The President's stringent controls on immigration from certain countries, which have faced staunch opposition, do not refer to Uzbekistan and would not have prevented the suspect from entering the United States.
A number of witnesses have said that at first they thought the attack was a Halloween prank.
Photos from the scene showed a badly damaged Home Depot rental pickup truck in the middle of the road.
A 14-year-old student from the nearby Stuyvesant High School told the New York Post: "What happened was there was a car crash… he came out of one of the cars. He had two guns."
New York Mayor Bill de Blasio said the attack 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."
Other officials urged New Yorkers to continue with their lives undeterred, stressing that a heightened security presence was not a sign that further attacks were expected. The city's annual Halloween parade was held as planned on Thursday.