Three Los Angeles County sheriff’s deputies assigned to the arson explosives detail were killed in an explosion at a law enforcement training facility.

Three deputies were killed Friday in an explosion at the L.A. County Sheriff’s Department’s Biscailuz Center Training Academy in East L.A., the deadliest incident for the agency in more than 160 years.

An explosion at a Los Angeles County Sheriff’s Department training facility killed three veteran deputies from the arson and explosives unit.