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.

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

The blast occurred during a bomb squad exercise at a Monterey Park academy; federal investigators are probing the cause