Salt Lake City police are investigating the death of a man on board an Amtrak train.

Someone aboard the train called 911 about 4:21 a.m. Friday to report a man in his 20s who was unconscious and not breathing. Firefighters and paramedics were at the Salt Lake City train station by the time the train pulled into town at 4:45 a.m.

"By the time they pulled into the station, the person was dead," Salt Lake City assistant Fire Chief Dan Andrus said Friday.

The man's body has been sent to the state medical examiner's office for autopsy. The train was headed from California to Chicago.