Eight people have died after a man drove a truck into pedestrians on a cycle path in Manhattan.
The attack was the deadliest in New York since nearly 3,000 people were killed on 11 September 2001.
A rented white pick-up truck struck cyclists and pedestrians in lower Manhattan, killing eight and injuring at least 12.
It happened at about 15:00 local time (19:00 GMT) on 31 October, on West St-Houston St path.
Computer science student Babatunde Ogunniyi, 29, saw the attack unfold.
"We were sitting outside of college, and I saw this truck coming, revving and swerving," he told the BBC. "He was going maybe 60 or 70 mph, in an area where the speed limit is 40 - it's a very congested area with lots of people.
"It hit the two people, I saw it hit them. Then he continued to drive down the walkway and bike lane. It hit a school bus and veered left.
"People started running towards the truck to see what was happening, and then the gunshots went off and everyone ran in the opposite direction."
The truck driver emerged holding a pellet gun and a paintball gun.
Eyewitnesses said the suspect shouted "Allahu Akbar" ("God is greatest") as he left the truck.
He was then shot in the abdomen by a police officer, named as 28-year-old Ryan Nash, who was at an unrelated call near the scene when he and two colleagues were alerted to the incident.
The suspect later underwent surgery for bullet wounds, and remains in custody. Police and the city's governor and mayor have praised Officer Nash's heroism in approaching the suspect.
Who is suspect Sayfullo Saipov?
Police named the attacker as 29-year-old Sayfullo Saipov, who entered the US from Uzbekistan in 2010 after winning residency in an annual visa lottery.
Mr Saipov has been charged by US prosecutors with causing the deaths of at least eight people and providing material support and resources to the Islamic State (IS) group. He has not sought bail and will remain in custody.
Prosecutors say he spoke freely to them, waiving his right to avoid self-incrimination while in custody.
According to the New York Times, Mr Saipov arrived in the country with a poor command of English and sought work as a truck and Uber taxi driver, living in Tampa, Florida and Paterson, New Jersey.
"He was a very good person when I knew him," Kobiljon Matkarov, an Uzbek national in Florida, told the New York Times. "He liked the US. He seemed very lucky and all the time he was happy and talking like everything is OK."
Mr Saipov married another Uzbek immigrant and has three children.
He is said to have been unlucky in finding employment and in the last three years, he grew a beard and developed a violent temper.
"I used to tell him: 'Hey, you are too much emotional. Read books more. Learn your religion first,'" Abdul said.
New York Governor Cuomo said Mr Saipov was radicalised in the US. It is now known that he left notes in his vehicle alluding to the Islamic State, written in Arabic. Multiple knives were also found inside of the hire vehicle.
Car-share service Uber said Mr Saipov had been working for them, and had passed its background checks. The company said it was "horrified by this senseless act of violence".
Police confirmed Mr Saipov had not been investigated in the past, but is believed to have previously come to federal authorities' attention as a result of investigation of others.
Police records show he was arrested in Missouri last year over a traffic fine.
What did the suspect say?
Mr Saipov appeared in court in a wheelchair on Tuesday and prosecutors say he spoke freely to them.
According to federal court papers, he said:
- He planned the attack for a year and carried out a trial run with a rental truck last month
- He intentionally chose Halloween because he believed there would be more people in the streets
- He originally planned to target the Brooklyn Bridge as well
- He wanted to display Islamic State (IS) flags on the truck, but decided not to draw attention to himself
- He was inspired by 90 graphic and violent propaganda videos found on his phone - in particular, one in which IS leader Abu Bakr al-Baghdadi asks what Muslims are doing to avenge deaths in Iraq
Mr Saipov was charged with one count of providing material support and resources to IS and another count of violence and destruction of motor vehicles.
New York Police's Deputy Commissioner John Miller said the suspect appeared "to have followed almost exactly to a 'T'" IS instructions on how to carry out such an attack.
The FBI says they have located a second Uzbek man, 32-year-old Mukhammadzoir Kadirov, who was wanted for questioning in connection with the attack. There are reports he is Mr Saipov's cousin.
Who were the victims?
Eight people are known to have died in total - two in hospital and six at the scene itself.
The deaths of five Argentines were confirmed by the country's foreign ministry. They were part of a group of ten friends in New York to celebrate the 30th anniversary of their graduation from a polytechnic college in the central city of Rosario.
The men - all reportedly aged 48 or 49 - were named as Ariel Erlij, Diego Enrique Angelini, Alejandro Damián Pagnucco, Hernán Diego Mendoza and Hernán Ferrucci.
Another of the friends, Martín Ludovico Marro, is being treated in hospital but the extent of his injuries is not known.
Erlij, a steel firm owner, helped pay for the friends' trip, La Nación newspaper reported (in Spanish). He was not able to fly out with his friends, and travelled to New York a day later by private plane, the Rosario newspaper La Capital reported.
In a photograph widely used by Argentine media outlets, eight of the men were seen together at the airport in Rosario, arms over each others' shoulders, wearing T-shirts saying Libre (Free).
La Capital said that early in their trip, they had travelled to Boston to spend time with Marro, who lives in the city. They then travelled down to New York and decided to cycle along the path near the World Trade Center.
Three days of mourning have been declared in Rosário, Clarín newspaper reported. President Mauricio Macri expressed his "deep condolences" for the victims' families on Twitter.
Ann-Laure Decadt, a 31-year-old from northern Belgium was also among those killed, her town's mayor said. The mother-of-two was visiting New York with her mother and two sisters.
"It's terrible to think that someone enjoying their holidays may die as a result of such an act," Francesco Vanderjeugd, the mayor of Staden in West Flanders, said.
Decadt and her husband have two sons, who are reportedly just three years old and three months old.
The two other victims, both American, were Darren Drake, 32, and Nicholas Cleves, 23.
Mr Drake, a project manager at Moody's Investors Service at the World Trade Center a few streets from the attack, was "the most innocent, delicate kid in the world", his father was quoted as saying.
The other victim, Nicholas Cleves, was a native of Boston living in New York.
In total 12 other people were injured. Four of those hurt were in the school bus - including two adults and two children.
Four of the injured were critical but have now stabilised. Five more are said to be serious and three have been released.
Authorities said injuries included a bilateral amputation and serious back and neck trauma.