An unidentified "adult male" apparently stepped off the San Antonio Station passenger platform into the path of a speeding Caltrain commuter at 5:08 p.m. Monday, according to Caltrain spokesperson Christine Dunn.
The train was a "limited stop" train that was going between 73 and 79 miles per hour, Dunn said.
The train was stopped some distance south of the station and other southbound trains were single-tracked on the northbound tracks starting at about 5:40 p.m., Dunn said.
A tall steel fence separates the tracks to prevent any crossover by pedestrians.
Caltrains were delayed between 30 and 60 minutes until after 7 p.m.
A Santa Clara County Medical Examiner and Coroner's Office official was still investigating the site as of 8 p.m.
Long strands of yellow "caution" tape prohibited pedestrians from entering the station as a dozen officials combed the scene. A white stretcher stood on the platform, empty. An abandoned shopping cart, filled with dark garbage bags, stood near a ramp leading to the platform.
A few passersby paused to survey the station.
Dunn said the death is the fifth track fatality of 2010, somewhat below the rate of 2009, when there 19 deaths on Caltrain tracks -- the second highest year since 1995, when there were fewer trains running at slower speeds.