CALIFORNIA - Rail service resumed Tuesday along the tracks where a Metrolink train collided head-on with a freight train and left 25 people dead four days earlier.

An Amtrak Surfliner was the first passenger train to use the newly repaired stretch of tracks, leaving the nearby Chatsworth station about 3:45 p.m. PDT. A Metrolink commuter train followed a short time later.

Only a few people boarded the commuter train in Chatsworth, and just three sat in the first car, the compartment that was the most damaged in Friday's collision.

Among those in the first car was regular rider Sal Garcia, who said he had been sick Friday and stayed home. Sitting in his usual seat was therapeutic, he said.

"It was really emotional. I sat down and started to cry, and that made me feel a lot better," Garcia said.

Also in the first car was LeeAnn Clifton, a visitor from northern California.

"This is a little eerie," she said.

The train was monitored closely by rail workers as it slowly passed the site of the crash. Residents along the route left their homes and waved as the train passed. Flowers were laid along the platform at the Simi Valley station.

Hours before service resumed, investigators conducted a visibility test to determine when the engineers involved the crash would have been able to see each other in the moments before the nation's deadliest rail disaster in 15 years.