DEVELOPING: An explosion at a military ammunition storage facility in Nevada during a Marine Corps training exercise killed seven U.S. Marines and wounded several others, military officials said.

The soldiers with the 2nd Marine Division were killed late Monday when a 60-millimeter mortar exploded during a live-fire training exercise at Hawthorne Army Depot as Marines were preparing to fire it, NBC News reports.

The cause of the incident remains under investigation. The identities of those killed were not released pending notification of their families, officials said.

"We send our prayers and condolences to the families of Marines involved in this tragic incident. We remain focused on ensuring that they are supported through this difficult time," said Maj. Gen. Raymond C. Fox. "We mourn their loss, and it is with heavy hearts we remember their courage and sacrifice."

Stacy Kendall, a spokeswoman for Renown Regional Medical Center, told NBC News the facility was treating eight people wounded in the blast.

Three were listed in serious condition; five were listed in fair condition. Kendall said the injuries included traumas and fractures.

Earlier, Russ Collier, an official at the facility, told KRNV-TV that the explosion was an accident unrelated to the ammunition that is stored at the military facility near the small desert community of Hawthorne.

The 147,000-acre depot, established in 1930, is about 140 miles southeast of Reno. The facility stores and disposes of ammunition, and provides long-term storage for industrial plant equipment. It is comprised of nearly 3,000 buildings — including igloos, supply warehouses and munitions sheds — throughout more than 230 square miles.

The facility had an operating budget of $270,000 and a payroll of $2.88 million in fiscal year 2009, according to its website.

Messages seeking comment from Hawthorne Army Depot officials were not immediately returned.

The Associated Press contributed to this report.

http://www.foxnews.com/us/2013/03/19...ne-army-depot/