An explosion at a Los Angeles Sheriff’s Department training facility on Friday killed three members of its arson and explosives unit, officials said.

The department said the explosion occurred about 7:30 a.m. at the Biscailuz Training Facility in East Los Angeles.

The department has not said what the deputies were doing at the time or what caused the explosion.

Officials were exploring whether there may be a connection to the discovery the previous day of “devices” at an apartment complex in Santa Monica, sheriff’s department spokesperson Nicole Nishida said. She did not specify what sort of devices they were.

The three members of the arson and explosives team responded that day to assist local police.

Law enforcement agencies were obtaining a warrant to search the complex for potential explosive material, and police evacuated residents, Nishida said.

The department on Friday evening identified the deputies killed as detective Joshua Kelley-Eklund, Detective Victor Lemus, and Detective William Osborn.

They served 19, 22, and 33 years in the department respectively, Los Angeles County Sheriff Robert Luna said.

“They have years of training,” the sheriff said at a news conference. “They are fantastic experts, and unfortunately I lost three of them today.”

Video footage captured by local news station KTLA 5 TV and NBC Los Angeles shows an LASD vehicle with a shattered rear windshield. A tarp over what appears to be an explosives trucks was also visibly damaged.

Luna said it took more than four hours to render the scene safe and the deaths were being investigated by the department’s homicide detectives, with the assistance of the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). No one else was injured, he said.

Gov. Gavin Newsom called it “a heartbreaking day for California.”

“Three members of @LASDHQ lost their lives in the line of duty—serving with courage and honor,” Newsom said in a post on X. “We will never forget their service to our communities.”

The governor’s office said Newsom was briefed.

“The Governor’s Office of Emergency Services … is in contact with the Sheriff’s Department and closely monitoring the situation, and has offered full state assistance,” the governor’s office said earlier Friday.

The office later said that members of the State Fire Marshal were helping with the investigation at the request of the ATF.

U.S. Attorney General Pam Bondi said in a post on X earlier on Friday that the explosion “appears to be a horrific incident.”

She added that “federal agents are at the scene and we are working to learn more” and called on people to “please pray for the families of the sheriff’s deputies killed.”

The Epoch Times has contacted the LASD’s media office for comment.

The Associated Press contributed to this report.