New York authorities have said that a gunman wearing a gas mask set off a smoke bomb and opened fire in a subway car on Tuesday, hitting at least ten people.
The suspect was at large as of 6pm local time (11pm UK time) and was described as dangerous by authorities.
Five people were in a critical condition but were expected to survive.
NYPD commissioner Keechant Sewell said the attack was not being investigated as terrorism, but that she was “not ruling out anything”.
Ms Sewell said the man was seen donning a gas mask in the train car as it was about to enter the station, then removed a canister from his bag and opened it.
“The train at that time began to fill with smoke. He then opened fire, striking multiple people on the subway and in the platform,” she added.
Governor Kathy Hochul warned the city’s residents to be vigilant.
“This individual is still on the loose. This person is dangerous,” the Democrat said at a news conference.
“This is an active shooter situation right now in the city of New York.”
Fire and police officials were investigating reports that there had been an explosion, but Ms Sewell said at a press conference just after noon that there were no known explosive devices.
The suspect has not been identified and the motive remains unknown.
“My subway door opened into calamity. It was smoke and blood and people screaming," witness Sam Carcamo told radio station 1010 WINS, saying he saw a gigantic billow of smoke pouring out of the N train once the door opened.
Brooklyn resident Yayha Ibrahim said he saw people running from the station, and decided to walk down into it to see what was happening.
“I saw a lady, she was shot right in her leg and she was screaming for help," he said. Rescue workers “did a good job of coming quick and fast, and the ambulance came in and they took her.”
The incident happened around 8.20am local time on a subway line that runs through south Brooklyn in a neighbourhood about a 15-minute train ride to Manhattan.
Local schools, including Sunset Park High School across the street, were locked down.
The shooting comes as New York City has faced a spate of high-profile incidents in recent months, including on the city’s subways.
One of the most shocking was in January when a woman was pushed to her death in front of a train by a stranger.
