Terrified New York City commuters were left trapped in a carriage with a gunman when a fight got out of control on Thursday during rush hour.

The shooting, which left one man in a critical condition after being shot in the head, occurred at about 4:45pm when a man, 32, was confronted by an “aggressive” 36-year-old commuter after boarding the train.

The shooting follows a series of high-profile assaults on commuters and transit workers on New York City subways that have left three dead this year.

Just over a week ago, Kathy Hochul, New York’s Democratic governor, deployed 750 National Guard members to the subway network in an attempt to crack down on crime.

The latest incident started as a verbal dispute between the passengers but escalated quickly into a fight as the train left Nostrand Avenue station in Brooklyn.

During the altercation, the 36-year-old man barked “I’ll beat you up” before hurling insults at the other man in an apparent attempt to instigate a fight.

The assailant then lunged at the man, pushing him onto the seats and punching him several times, footage posted online shows.

“Come on, there’s babies on here!” one woman can be heard pleading on the video.

As the fight continued, a woman could be seen appearing to stab him multiple times in the back.

It was not immediately clear that she had a weapon but the 36-year-old was heard repeatedly yelling out “you stabbed me?” to the woman, as blood seeped through his shirt.

At one point, the aggressor, dressed in all black, flashed a sharp object believed to be a knife or a razor blade before digging through his jacket to retrieve a gun, said Michael Kemper, the police department chief of transit, at a press conference.

As the gun was pulled, commuters screamed and rushed to the opposite side of the train car with several passengers ducking for cover.

The man being beaten up yanked the gun from the assailant before firing several rounds, according to reports. At least four shots can be heard in footage, with the assailant reportedly being shot in the head in front of dozens of commuters.

Passengers can be heard desperately yelling “get me out” right before the car doors were opened at the Hoyt–Schermerhorn station, as officers with their guns drawn rushed into the train car and arrested the shooter.

Joyce Philippe, an ABC journalist who was on the train in a different car, posted a video to social media where one woman can be heard screaming “where’s the NYPD? Oh, my God”.

“People were crying, praying, huddled amongst each other . . .,” Ms Phillipe told The New York Post. “It was a very fearful moment”.

It’s not yet clear whether the victim-turned-shooter will face any charges for Thursday’s incident, with police stating that the “victim appears to be the aggressor”.

Some locals were left puzzled on Thursday and left questioning the use of the National Guard when they learned that none were at Hoyt–Schermerhorn station.

Z‌ara Jones, a New York resident, told The Post: “I thought they were bringing in the National Guard and extra to stop these kinds of things from happening. If they can’t stop it, who can?”

“Why are shootings on the subway becoming a regular occurrence? There’s too many guns and too many people willing to use them indiscriminately. It makes me sick”, Ms Jones added.

Since the beginning of the year there have been eight shooting victims on the New York City transit system, up 700 per cent from the same time period in 2023.

The National Guard was introduced to patrol the subway and perform bag checks but passengers had the right to refuse.