The as yet unidentified man was struck at 7:40 p.m. by the 7:09 p.m. train as it was moving just east of the Broadway Station in Queens, the official said.
Sam Zambuto, the LIRR spokesman said it is not know why the man was there. "It was an unauthorized person on the tracks," he said.
"The MTA police are investigating the incident as a possible suicide," Zambuto said.
The incident caused the cancellation of that train and two other following trains, Zambuto said, as well as delays of 10- or 15- minutes to other trains in both directions.
Some passengers were delayed up to an hour in reaching their destinations, Zambuto said.