SANTA ANA, Calif. (AP) — A Southern California police officer who killed an unarmed 18-year-old won't face criminal charges.

The Orange County district attorney's office says there's insufficient evidence to show Santa Ana Detective David Prewett committed a crime when he shot Steve Salgado in January.

The decision came in a July 7 report.

Police say Prewett was with an anti-gang patrol when they approached a car blocking an alley in a bad neighborhood. Salgado, a gang member, got out and ran as officers approached.

Police say during the chase, Salgado kept a hand on something in his pocket and officers believed he might have a knife or gun. Officers said Salgado was shot after pulling something from his pocket and looking back at Prewett.

Police later found cellphones and apparent drug paraphernalia but no weapon.