It was not immediately clear what caused the blast at the Los Angeles County Sheriff’s Department’s Biscailuz Training Academy center.

The explosion was reported about 7:30 a.m. at the Biscailuz Training Facility, Los Angeles County Sheriff’s Department spokesperson Nicole Nishida said. It was not immediately known what caused the explosion or what the deputies were doing at the time.

An explosion at a Los Angeles County Sheriff's Department training facility Friday left three deputies dead, officials said. The blast was reported just before 7:30 a.m. Pacific and occurred at the Biscailuz Center Training Academy in East L.