The 41-year-old officer died Sunday morning from a gunshot wound in the police station's locker room.
It is believed he was alone at the time. Investigators are trying to determine if the shooting was an accident or a self-inflicted act.
The officer, a Downey resident, was married and was sworn in to the police department earlier this year in what was described as a second career.
The officer's name has not been released pending the notification of family.