The explosion that killed seven Marines during mortar training in March at the Hawthorne Army Depot in Nevada was caused by human error, the Marine Corps said Wednesday.
“The Marines employing one of the mortars did not follow correct procedures, resulting in the detonation of a high explosive round at the mortar position,” the Marine Corps said in a statement about the results of an investigation.
Also, the Marines “had not conducted appropriate preparatory training leading up to the live-fire event,” the statement said.
The seven enlisted Marines from Camp Lejeune, N.C., were killed March 18 when a 60-millimeter mortar round exploded prematurely during a nighttime exercise. Seven other Marines and a Navy corpsman were injured.
Training with 60-millimeter mortar rounds was halted after the incident but resumed within days.
The Marine investigation “determined that the mortar system functioned properly at Hawthorne and found no reason to question the safety of the system when it is employed as designed and as Marines are trained to employ it,” the statement said.
No criminal charges will be filed because of the incident, the Marine Corps said.
The Marines, from the 1st Battalion, 9th Marine Regiment, were training at Hawthorne after finishing up at the nearby Marine Corps Mountain Warfare Training Center in Bridgeport, Calif.
Brig. Gen. James W. Lukeman, commander of the 2nd Marine Division, has relieved three officers as a result of the investigation: Lt. Col. Andrew McNulty, commander of the 1st Battalion; Capt. Kelby Breivogel, commander of Alpha Company; and Chief Warrant Officer 3 Douglas Derring, the battalion’s infantry weapons officer.
Lukeman did so because he lost trust and confidence in their ability to ensure proper preparation for and conduct of live-fire training, the Marine Corps said.