4 Marines killed while performing maintenance at Camp Pendleton By Tony Perry November 13, 2013, 9:10 p.m. SAN DIEGO - Four Marines were killed Wednesday while performing maintenance on an artillery range at Camp Pendleton, the Marine Corps said. Only limited details of the accident were released. Names will be announced 24 hours after families are notified, the Marines said. "Our first priority is to provide the families with the support they need during this difficult time," said Brig. Gen. John Bullard, commanding general of Marine Installations West - Camp Pendleton. The accident occurred in the Whiskey-Zulu artillery range in the central portion of the base, where a live-fire exercise was scheduled for Wednesday. Clearing ordnance from the range is part of the maintenance needed for such an exercise but it was unclear if that was the cause of the accident, a base spokesman said. Investigators have determined that the accident was not caused by live firing, the spokesman said. In March, seven enlisted Marines from Camp Lejeune, N.C., were killed during mortar training at the Hawthorne Army Depot in Nevada. The premature explosion of the 60-millimeter mortar round that killed the seven was later determined to have been caused by human error in using a mortar, the Marine Corps said. A lieutenant colonel, a captain and a chief warrant officer were relieved of command as a result of the investigation.