The incident occurred shortly after 5 a.m. near the 5 Freeway and Templin Highway.
During the later investigation, officials learned the officer had been involved in a traffic collision. The incident led to a physical altercation at which time the suspect shot the officer in the arm with his own gun.
The officer suffered non life-threatening injuries and was expected to be OK.
The suspect remains on the loose.
No other information has been released.
The Los Angeles Sheriff's Department's homicide detectives are investigating the case.
Anyone with information on this incident was urged to contact the Los Angeles County Sheriff's Department's Homicide Bureau at (323) 890-5500.