WHITTIER, Calif. — A city police officer was killed and another wounded in a shooting Monday while they were trying to help a man who had been in a traffic accident in Whittier, officials said.

Police said the 26-year-old suspect is a known gang member who had been paroled about 10 days earlier.

The two officers had responded to a report of a traffic accident and approached the vehicle when they were shot by one of the people in the vehicle, said Lieutenant John Corina of the Los Angeles County Sheriff’s Department.

Police returned fire, wounding the suspect. His name was not released, and his condition was not immediately available. The slain officer’s name was not released.

Investigators did not know why the suspect suspect opened fire.

‘‘We’re still looking into that,’’ Corina said. ‘‘We believe the car he was in [was] a stolen car, so that I’m sure is one of the reasons.’’

The wounded officer was in stable condition, said Nicole Nishida, a spokeswoman for the Sheriff’s Department. The other people involved in the accident were not injured.

‘‘It’s extremely tragic,’’ Corina said. ‘‘You just never know when officers respond to a call what they are going to run into.’’

The Whittier Police Department has about 125 sworn officers who police Whittier and Santa Fe Springs in southeastern Los Angeles County.

Associated Press