Southbound Caltrain No. 386 struck the man at the station at 385 First Ave. at about 7 p.m., spokeswoman Christine Dunn said. He was taken by ambulance to Central Park, and a helicopter then took him to Stanford Medical Center, where he was pronounced dead.
Dunn said preliminary reports indicate the man was lying on the tracks when he was struck and that the engineer could not stop the train in time to avoid hitting him.
Passengers on the train got off at the station and boarded the next southbound train.
The incident caused delays of up to about 40 minutes in both directions. Both tracks were open by about 7:30 p.m.