SAN DIEGO – A teenager died after falling off his bike and hitting his head on train tracks, police said Monday.

The 14-year-old boy was not wearing a helmet when he fell on the railroad tracks at Imperial Avenue and 60th Street  in Encanto around 2:30 p.m. Monday, San Diego police said.

Witnesses said the boy was riding his bike at a high rate of speed down a steep hill, hit a fence, was launched about 10 feet into the air, then hit his face on the tracks.

Trolley service was expected to be interrupted while the investigation continued. Police do not believe a train played a part in the boy’s death.

San Diego police were investigating the incident.

Imperial blocked at 61st & 62nd. #SDPD : teen boy died after falling onto trolley tracks, hits head @fox5sandiego pic.twitter.com/wyl42kSb8n

— Kristina Audencial (@KrisFox5SD) February 15, 2016