Authorities say it happened just before 5 a.m. Monday in unincorporated South Los Angeles.
A Sheriff's Department statement says parked sheriff's deputies heard what sounded like gunfire coming from a passing pickup truck.
While chasing the truck, deputies say a passenger shot at their patrol car.
A short time later, the passenger got out of the slow-moving truck and was shot. Three other people in the truck escaped.
Authorities say the wounded man is expected to survive and no gun was found at the scene. His name hasn't been released.
No deputies were wounded.