Four police officers were killed on Sunday morning in a Washington state coffee shop at 8am PST.
Maurice Clemmons, 37, was identified by police as a person of interest in the shooting and has a troubled criminal history.
Sunday's incident was the first time the Lakewood police department lost any officer to a shooting.
The slain officers were in uniform and were wearing bulletproof vests when shot. They were pronounced dead on the scene.
The officers were identified as Sergeant Mark Renninger, 39; Ronald Owens, 37; Tina Griswald, 40; and Greg Richards, 42.