The incident happened around 9:30 p.m. at Trask Avenue and South Euclid Street, just north of the Garden Grove Freeway.
Investigators said the police sergeant was struck by a sedan as he was driving his unmarked police car through the intersection.
The force of the collision caused the police car to end up on the center median. The other car ended up on the sidewalk.
The police sergeant and the 23-year-old male driver of the other car were taken to nearby hospitals for non-life-threatening injuries.
The driver of the other car is expected to be arrested for driving under the influence, authorities said.
The California Highway Patrol is investigating the crash.
Anyone with information about the incident was asked to contact police at (714) 741-5704.