Eyewitnesses have spoken of their shock after a car rode onto the pavement and ploughed into a crowd in Times Square, New York,
Despite official police reports it was an accident, pedestrians said the actions of a driver appeared to be "intentional".
At least one person has died and 13 people were hurt.
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Video shows wrecked car that drove into pedestrians in Times Square
"Bodies were flying, he was running over people, it was like nothing I’d ever seen," Julie Fallo told Gothamist. "Everyone thought it was a terrorist attack and ran into buildings screaming. People were trying to get off the street, as if he was going to jump off the car and start shooting."
Ms Fallow said she thought the crash was deliberate, adding: "He went across going straight on the street and hit so many people that it slowed his car down and he just kept going."
"The people were slowing down his car but he was speeding up. We don’t understand. I don’t understand how that’s possible, I can’t imagine how you could keep going."
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Another bystander told CBS: "Everyone was just running. Everyone was concerned for their lives."
Other witnesses described people lying in the streets, including one person covered in a bloodstained blanket.
Police arrested a 26-year-old driver but said they believed the incident was not related to terrorism.
The driver had a history of drunk-driving and was being tested for alcohol, the AP reported.
Footage posted to social media showed a man being led into a police car by numerous officers. Emergency workers swarmed on the area, an internationally known tourist hub, and it was closed off.
President Donald Trump has been made aware of the incident, White House Press Secretary Sean Spicer said.