The Colma BART station was shut down after a body was found on the tracks.
The Colma Fire Protection District responded to the incident, which was reported at about 9:10 a.m.
The station reopened at 11:20 a.m.
BART spokesman Jim Allison told Bay City News the victim was under a train.
The San Mateo County coroner's office responded to the scene to remove the body, and BART police are investigating the death, Allison said.
There was no immediate information about the victim's age or sex.