CAMP PENDLETON, Calif. (AP) — A dropped or kicked grenade was the "most probable cause" of an explosion that killed four Marines during a training exercise last year at Camp Pendleton and a captain and master sergeant who were in charge were relieved of their duties, a base spokesman said Thursday.
The Nov. 13 blast occurred as ordnance disposal specialists were collecting unexploded rounds from a firing range at the San Diego County base for demolition — part of their training in the dangerous work of bomb disposal.
A Marine investigation report released Thursday indicated that a 40-mm grenade was accidentally "dropped, kicked or bumped," exploded and set off several dozen rounds that had been collected in a demolition pit, Capt. Ryan Welsh said.
However, the report listed the exact cause of the explosion as "indeterminate" and it may never be known.
"The only individuals with direct observations are deceased," Welsh said.
The captain and master sergeant who were conducting the ordnance disposal training were relieved of their duties on Tuesday — a move that potentially could end their careers.
The two lost their positions in charge of the base explosive ordnance disposal section "for loss of trust and confidence in their ability" to prepare for and conduct the training and for "lack of adherence to established norms," a base statement said.
For instance, they permitted the trainees to hand each other live ammo, Welsh said.
The explosion killed Staff Sgt. Mathew R. Marsh, 28, of Long Beach, Calif.; Sgt. Miguel Ortiz, 27, of Vista, Calif.; Gunnery Sgt. Gregory Mullins, 31, of Bayou L'Ourse, La., and Staff Sgt. Eric W. Summers, 32, of Poplar Bluff, Mo. All previously had served in Iraq, Afghanistan or in both countries.
A Navy Hospital Corpsman and two Marines near the accident had minor injuries.
In the wake of the explosion, Pendleton and other Western Marine bases were ordered to review and revise their explosive ordnance detail training, Welsh said.
Those bases are Marine Corps Air Station Miramar and Marine Corps Logistics Base Barstow, both in California, and Marine Corps Air Station Yuma in Arizona.
This is a story update. The previous story is below.
SAN DIEGO (CNS) - An explosion that killed four Marines at Camp Pendleton last fall likely occurred when a service member accidentally mishandled a piece of ordnance, according to military investigative results released Thursday.
In light of the findings, the officer and staff non-commissioned officer in charge of the base explosive-ordnance disposal section were relieved from duty this week by Brig. Gen. John Bullard, commander of Marine Corps Installations West, according to a statement from the Oceanside-area USMC installation.
The stated reasons for removing the squad leaders from their posts Tuesday were "loss of trust and confidence in their ability to ensure proper preparation for and conduct of EOD proficiency training and lack of adherence to the established norms."
A base spokesman said regulations precluded him from releasing the names of the officers who lost their assignments due to the explosion.
The Nov. 13 blast claimed the lives of Sgt. Miguel Ortiz, 27, of Vista; Staff Sgt. Mathew R. Marsh, 28, of Long Beach; Gunnery Sgt. Gregory J. Mullins, 31, of Bayou L'Ourse, La.; and Staff Sgt. Eric W. Summers, 32, of Poplar Bluff, Mo.
Two other Marines and a Navy corpsman suffered non-fatal injuries in the accident.
The detonation occurred while personnel were sweeping an artillery range for unexploded munitions.
"The investigation established that the exact cause of the explosion is indeterminate, as the only individuals with direct observation are deceased,'' according to the statement. "Based on the findings of the investigation, the most probable cause of the explosion is a M430/A1 40 mm high-explosive dual-purpose round was dropped, kicked or bumped in the demolition pit.''
In addition to removing the officers from the ordnance-disposal unit, Bullard ordered an immediate review and revision of existing policies and procedures for EOD training at all Marine Corps Installations West ranges.
Revisions will include a requirement for more focused risk-management training, specific coordination rules for all EOD training requests, mandatory adherence to range survey requirements and more safety training for EOD personnel, officials said.
USMC officials were "deeply saddened by the tragic loss'' of the personnel during their "inherently dangerous'' training at Camp Pendleton, Bullard said. "Their loss is felt throughout the Marine Corps.''