Light bars on an ambulance.
File photo.

A man riding an off-road vehicle was killed Saturday night after crashing in the San Gabriel River flood control channel near Wardlow Road in Long Beach, authorities said.

Police said the man was operating an ATV “at a high rate of speed when he possibly lost control and fell from the vehicle” at about 7 p.m. at the river channel near Wardlow Road. The ATV was located a distance away from the driver, and authorities don’t know if the vehicle landed on him or whether he was thrown from the vehicle, police said.

Park rangers attempted lifesaving measures, but the man was declared deceased, police said.

The man is believed to be in his 20s, Long Beach Fire Department spokesman Brian Fisk said. The identity of the man will be released by the Los Angeles County Coroner’s office pending notification of next of kin.

City News Service contributed to this report.