BALDWIN PARK — A teenager was knocked unconscious with a blow to the head from behind and robbed Tuesday, police said.

The crime took place about 6:50 p.m. at Central and Big Dalton avenues, Baldwin Park police Sgt. Darryl Kosaka said.

The teenage victim didn’t see anything before he was attacked, the sergeant said. It was unclear whether he was struck with some type of weapon.

When he awoke, he found his iPod, cell phone and wallet were missing, Kosaka said. The injury was not believed to be serious.