Several people have been shot and injured at a subway station in New York City during a morning rush hour attack that left commuters bleeding on a train platform.

Initial reports indicated five people had been shot at the 36th Street station in Brooklyn’s Sunset Park area, law enforcement sources said.

Fire personnel responding to reports of smoke at the station at around 8.30am local time (1.30pm BST) found at least 13 people were hurt, but – aside from the five people who suffered gunshot wounds – there were no details on what those injuries entailed.

Preliminary information indicates that a suspect fled the area wearing a construction vest and a gas mask.

Photos and video from the scene showed people tending to bloodied passengers lying on the floor of the station and the air filled with smoke.

Fire and police officials were investigating reports that there had been an explosion, but the police department tweeted that there were “no active explosive devices at this time”.

Multiple smoke devices were found on the scene, mayoral spokesperson Fabien Levy said.

Eyewitness Sam Carcamo told radio station 1010 WIN: “My subway door opened into calamity. It was smoke and blood and people screaming.”

He added that he saw smoke pouring out of the N train once the door opened.

A bystander video shows people lying on the subway platform amid what appeared to be puddles of blood, as a loudspeaker announcement told everyone on the smoke-hazy platform to get on a train.

Inside a subway carriage, one person could be seen lying on the floor, encircled by others. Outside the station, a police officer yelled: “Let’s go! Get out of the way!”

Trains servicing that station were delayed during the morning rush hour.

The incident happened on a subway line that runs through south Brooklyn in an area a 15-minute train ride to Manhattan. Local schools, including Sunset Park High School across the street, were locked down.

Police officers were canvassing 4th Avenue, the station’s cross-street, asking witnesses whether they were on the train. A sea of emergency lights was visible from at least a dozen blocks away, where a police cordon was set up.

The shootings come as New York City has faced a spate a shootings and 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.

Mayor Eric Adams, a Democrat a little over 100 days into his term, has made cracking down on crime – especially on the subways – a focus of his early administration, pledging to send more police officers into stations and platforms for regular patrols.

It was not immediately clear whether officers had already been inside the station when the shootings occurred.