AP file photo

This May 20, 2005 file photo shows storage bunkers at the U.S. Army Depot in Hawthorne, Nev. Seven Marines from a North Carolina unit were killed and several injured in a training accident at the Hawthorne Army Depot, the Marine Corps said Tuesday, March 19, 2013. The cause of the accident, that occurred shortly before 10 p.m. PST, Monday, March 18, is under investigation, officials said in a statement from the 2nd Marine Expeditionary Force at Camp LeJeune, N.C. The Hawthorne Army Depot stores and disposes of ammunition. The facility is made up of hundreds of buildings spread over more than 230 square miles.