A person was struck and killed by a southbound Caltrain past the Blossom Hill station in South San Jose about 7:25 p.m., officials reported.
The person was trespassing on Caltrain tracks at the time, a spokesman said.
All trains in the area of the incident are being held as 8:15 p.m.
There were 23 passengers on the train at the time of the collision, but no injuries onboard were immediately reported.
Buses were being dispatched by the Valley Transit Authority to the Blossom Hill station to pick up those passengers.
The track reopened at regular speeds at about 9 p.m.
It was Caltrain's fifth fatality of the year.