An explosion in East Los Angeles Friday morning killed three Los Angeles County Sheriff’s deputies who were moving undetonated ordnance recovered the night before.

The blast occurred at 1060 N. Eastern Ave. at about 7:30 a.m., the Los Angeles County Fire Department said. That address corresponds with the LASD’s Biscailuz Center Training Academy.

Three people are confirmed dead, and a source tells KTLA 5 that those involved were deputies.

Additional injuries have also been reported, though the number and nature of them has not been disclosed.

Aerial footage from Sky5 shows an LASD vehicle with a shattered rear windshield and a nearby backpack on the parking lot asphalt near what appears to be the department’s explosives trucks.

Additionally, a tarp over the bomb trucks was visibly damaged, presumably in the explosion.

The cause of the explosion has not yet been disclosed, but KTLA’s Eric Spillman reports that deputies were moving unexploded ordnance recovered Thursday night when they detonated.

The blast has prompted governmental agencies at all levels to offer their help and provide assistance with the investigation.

KTLA’s Annie Rose Ramos reports that the Los Angeles Police Department’s bomb squad arrived to the training center at about 8:45 a.m.

Federal officials say they’re assisting as well.

“I just spoke to [U.S. Attorney Bill Essayli] about what appears to be a horrific incident that killed at least three at a law enforcement training facility in Los Angeles,” Attorney General Pam Bondi wrote on social media. “Our federal agents are at the scene and we are working to learn more. Please pray for the families of the sheriff’s deputies killed.”

Gov. Gavin Newsom has also “offered full state assistance.”

Luis Zuniga contributed to this report. Check back for updates to this developing story.