Four Marines killed in Camp Pendleton explosion

Four Marines were killed Wednesday during an operation to clear a range of unexploded ordnance at Camp Pendleton in Southern California, a Marine official said.

The accident happened at 11 a.m. PST during a range maintenance operation at the San Diego County coastal base.

The Marines were clearing the range of unexploded ordnance, and it was not a live firing range, said a Marine official with knowledge of the incident who spoke on condition of anonymity because he was not authorized to speak publicly.

The identities of the dead were withheld pending notification of relatives. No further details were released.

"We offer our heartfelt prayers and condolences to the families of the Marines lost today in this tragic accident," said Brig. Gen. John W. Bullard, commanding general of Marine Corps Installations West at Marine Corps Base Camp Pendleton. "Our first priority is to provide the families with the support they need during this difficult time."

The deaths come about eight months after a mortar explosion killed seven Marines during a live-fire training exercise in Nevada.

A military investigation determined human error was to blame for that accident. According to the findings, a Marine operating a 60 mm mortar tube and ammunition did not follow correct procedures, resulting in the detonation of a high explosive round at the mortar position.

The investigation also determined that the mortar team involved in the accident had not conducted "appropriate preparatory training."

Al Jazeera and The Associated Press