SAN BERNARDINO – A freight train struck and killed a man who was laying on railroad tracks in San Bernardino County, forcing the cancellation of Friday morning commuter trains for hours, authorities said.

A BNSF train hit 44-year-old David Martinez of Riverside just before midnight on Thursday in the community of Grand Terrace. It is unclear whether he was already dead before he was struck, county sheriff's spokesman Arden Wiltshire said.

The train immediately stopped. No injuries were reported.

Two tracks were shut down. Two Metrolink commuter trains heading from San Bernardino to Oceanside were canceled and a third was delayed more than an hour, spokeswoman Denise Tyrell said.

One track reopened at 7:45 a.m. but trains went through the area at a reduced speed, Tyrell said.

An autopsy was ordered.