One person was killed and five wounded following a dispute between two groups of teenagers at a New York City subway station on Monday at the start of the evening rush hour, authorities said.

The gunfire broke out on an elevated train platform in the Bronx at around 4.30 pm, a time when stations throughout the city are filled with kids coming home from school and many workers are beginning their evening commute.

A 34-year-old man was killed, police said. The wounded included a 14-year-old girl and 15-year-old boy, and three adults, aged 28, 29 and 71. Some of the victims were believed involved in the dispute and others were waiting for the train, authorities said, describing four of the injuries as serious.

"We don't believe this was a random shooting. We do not believe that this was an individual indiscriminately firing into a train or a train station," NYPD's chief of transit, Michael Kemper, said at a news conference. "This incident today occurred as a result of two groups that started fighting while on a train."

The gunfire erupted when the train pulled into the station, Kemper said, striking people on the platform.

"The doors opened up and at least one of the individuals in that group, or in the two groups, took out a gun and fired shots," Kemper said. "People started running off the train onto the platform and more shots were fired on the platform."

A hunt was on for at least one shooter, who fled the scene.

"The train was coming and there were two kids yelling," witness Efrain Feliciano (61) told the Daily News. "There were at least six shots."

"I saw sparkles as the bullets hit the wall," Feliciano said. "A woman was holding a child screaming."

Video from television news helicopters showed a subway train stopped at the station and orange evidence cones on the platform, which is three stops north of Yankee Stadium. Trains were still running through the station on an express track, but weren't stopping as police investigated.

Fear of violence on the subway system spiked after a string of incidents in recent years, but overall, crime in New York City has been plummeting since a surge at the height of the COVID-19 pandemic.

The number of people shot citywide dropped 39 per cent last year compared to 2022. Killings on the subway system also dropped last year, from 10 to 5.

"Not only people must be actually safe, but what we have done in lowering crime, they must feel safe," Mayor Eric Adams said on 1010 Wins radio, "and something like this can send shockwaves throughout our entire system."