The training accident that killed seven Marines during a live firing accident was caused by human error when the 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," a Marine spokesman said.
The nighttime live-fire exercise occurred on March 18 at the Hawthorne Army Depot in Nevada. The accident occurred when a mortar exploded. Along with the seven Marines who died, another seven Marines and one sailor were hurt.
Brig. Gen. James Lukeman, commander of the 2nd Marine Division, led the investigation. Along with faulting the individual Marine, Lukeman's investigation also found that the mortar team did not execute "appropriate preparatory training" ahead of the live fire training.
The Marine Corps has already moved to issue punishment for mistakes made in relationship for the live fire. Battalion Commander Lt. Col. Andrew McNulty was relieved on May 8. Lukeman also relieved Company Commander Capt. Kelby Breivogel and Chief Warrant Officer 3 Douglas Derring, the battalion's infantry weapons officer.
Lukeman said in a release that those officers were relieved because "he lost trust and confidence in their ability to ensure proper preparation for, and conduct of, live-fire training events."
- Associated Press contributed to this report.