LOS ANGELES — A grenade is missing from the scene of an explosion that killed three Los Angeles County sheriff’s deputies, authorities said Friday.

The July 18 blast at a sheriff’s department training facility killed three experienced deputies on the arson and explosives team.

The deputies were working on two grenades that had been taken into custody by authorities. One of the grenades detonated, and the other is unaccounted for, Sheriff Robert Luna said, according to the Bureau of Alcohol, Tobacco and Firearms, which is investigating the explosion.

Luna said authorities X-rayed special enforcement bureau vehicles, searched all around the blast area and examined office spaces and even the gym and haven’t found it.

“You get the drift. We have looked at everything out there that we possibly could,” he said, adding that no one from the public has had access to the area.