HAWTHORNE, Nev. -- A mortar shell explosion killed eight Marines and injured seven more during mountain warfare training in Nevada's high desert, prompting the Pentagon to immediately halt the use of the weapons until an investigation can determine their safety.
The explosion occurred Monday night at the Hawthorne Army Depot, a facility used by troops heading overseas, during an exercise involving the 2nd Marine Expeditionary Force from Camp Lejeune, N.C. Several Marines from the unit were injured in the blast, authorities said.
A mortar round exploded in its firing tube during the exercise, Brig. Gen. Jim Lukeman told a news conference at Camp Lejeune. He said investigators are trying to determine the cause.
The Pentagon expanded a temporary ban to prohibit the military from firing any 60 mm mortar rounds until the results of the investigation. The Marine Corps said yesterday a "blanket suspension" of 60 mm mortars and associated firing tubes is in effect.
The 60 mm mortar is a weapon that traditionally requires three to four Marines to operate, but it's common during training for others to observe nearby. The firing tube is supported in a tripod-like design and fires roughly a 3-pound shell, some 14 inches in length and just over 2 inches in diameter.
The identities of those killed won't be released until 24 hours after their families are notified.
"We send our prayers and condolences to the families of Marines involved in this tragic incident," said the force's commander, Maj. Gen. Raymond C. Fox.
The mortar has changed little since World War II and remains one of the simplest weapons to operate, said Joseph Trevithick, a mortar expert with GlobalSecurity.org.
"Basically, it's still a pipe, and it's got a firing pin at the bottom," Trevithick said.
Things that could go wrong include a fuse malfunctioning, a problem with the barrel's assembly and a round prematurely detonating inside the tube, he said.