New York: It’s a subway rider’s worst nightmare: being pushed onto the tracks. The nightmare happened in midtown Manhattan this week when, according to witnesses, one man shoved another in front of an oncoming train, which crushed the victim to death before horrified onlookers.

Police were questioning a man Tuesday in connection with Monday’s attack on Ki-Suk Han, 58, of the New York borough of Queens, who witnesses said had intervened as the pusher harassed others waiting for a train.

The identity of the man being questioned was not released, but police said he was 30 years old and a regular in the area, sometimes working with street vendors on the sidewalks near the subway station.

Late Tuesday, police said he had implicated himself in the attack. No charges were expected to be announced before Wednesday.

Part of Monday’s incident at the station at 49th Street and Seventh Avenue was caught on camera. A video and photographs of the alleged pusher were circulated across the city. Witnesses said the pusher appeared to be disturbed and had been muttering and frightening others on the platform as they waited for a train about 12.30pm.

Han, who New York Police Commissioner Raymond Kelly has said was headed to the Korean consulate to renew his passport, apparently confronted the man and told him to leave others alone. A video released by police shows a tall man wearing a knit cap and a white T-shirt, facing the much smaller Han, who is heard demanding that Han “leave me the ... alone.”

He points up the platform and is heard on the videotape telling Han to go and wait for his train. As the argument ensued, others on the platform moved away from the two men.

Then, witnesses said, the man pushed Han onto the tracks. Han stood up, faced the train and began trying to climb off the tracks as the train sped towards him. One witness facing the oncoming train repeatedly snapped his camera in hopes the flash would warn the conductor early enough to stop. Others on the platform waved their hands and yelled at the conductor. The train slammed on its breaks but could not stop in time, crushing Han between the side of the platform and the train.

The New York Post published a photo on its front page Tuesday of Han desperately looking at the train, his arms reaching up as the train bore down on him. It was shot by the witness with the camera, freelance photographer R Umar Abbasi, who said he used his flash to try to warn the conductor but wasn’t strong enough to lift Han off the tracks, The Associated Press reported.

“I wanted to help the man, but I couldn’t figure out how to help,” Abbasi said in a video interview on the Post’s website. “It all happened so fast.” Passengers on the train heard a strange “thud” as the train came into the station.

As a woman on the platform tried to perform CPR on Han, the man said to have pushed him fled up the stairs and out of the station, melting into the crowds near Times Square.

Mayor Michael R Bloomberg said at a news briefing that it appeared the pusher had “a psychiatric problem.” Han, he said, “tried to break up a fight or something and paid for it with his life.” Such crimes are rare in the 24-hour subway system, which carries nearly 5.3 million riders daily.

Two other people were pushed onto subway tracks in separate incidents earlier this year, and both survived. In a third incident, a man died after falling onto subway tracks during a fight with another subway rider. The man was hit by a train and killed.

In 1999, two high-profile pushing incidents prompted passage of a state law allowing courts to require that some people diagnosed with mental illnesses accept treatment and medication before being released from psychiatric facilities. Both incidents involved mentally ill men who had been released from hospitals without medication.

One victim was killed, the other survived but lost his legs. Both incidents helped prompt passage of Kendra’s Law, named for Kendra Webdale, 32, who died after being pushed in front of a train in January 1999.