A 19-year-old Livermore man was struck and killed by a freight train early Saturday morning east of downtown Livermore, police reported.

Tyler Richard Booth had massive head trauma, according to the Alameda County Coroner's Office.

The crew of the Union Pacific Railroad train told police that they saw a man along the side of the tracks east of the Junction Avenue railroad crossing shortly before the train struck him about 2:33 a.m.

The crew stopped the train and reported the collision.

Police were attempting to determine why the victim was so close to the tracks that the train hit him, police Lt. Lance Bye said.

The man appeared to be by himself, the train crew told police.