By Jessica Michele Herring (staff@latinospost.com) | First Posted: Nov 14, 2013 10:01 AM EST

Four Marines were killed on Wednesday in an accident at Camp Pendleton in Southern California, according to officials. 

The Associated Press reports that the accident occurred at 11 a.m. during a range maintenance operation at the San Diego County coastal base. The Marines were clearing the range of unexploded artillery, and it was not a live firing range. No other details were released. The Marines involved in the accident were Explosive Ordnance Disposal Marines, NBC 7 San Diego confirms. 

An official told NBC 7 that the incident occurred in the Zulu impact area, which is located near the center of the base. The impact area is where Marines fire artillery and drop aircraft bombs. 

The official said that "range maintenance" is a broad term used to describe the upkeep on firing ranges and can include anything from clearing artillery to mowing grass. 

The identities of those killed were withheld, and are awaiting approval for release by relatives. 

"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."

It is not the first time a Marine had been killed at Camp Pendleton. This past February, a Marine at the camp was killed while skydiving in an active-duty training exercise in Riverside County. 

A year before, a 23-year-old Marine died in a car accident during a training exercise. The fatal accident also comes about eight months after a mortar explosion killed seven Marines during a live-fire training exercise in Nevada. A subsequent military investigation declared human error to be the cause of the accident.

According to the investigation, a Marine operating a 60mm mortar tube and ammunition did not follow correct procedure, which resulted in a high explosive round being detonated at the mortar position. 

The investigation also found that the mortar team involved in the accident had not gone through "appropriate preparatory training."

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