Las Vegas, NV (KTNV) -- Seven Marines are dead and several others remain hospitalized after a mortar exploded during a training accident at a rural Nevada Army depot.
The incident happened late Monday night at the Hawthorne Army Depot, located southeast of Reno.
A 60-mm mortar round exploded, killing seven Marines instantly. At least five others suffered injuries ranging from minor to critical.
Their identities have not been released.
The team from the 2nd Marine Division at Camp LeJeune was participating in live fire and maneuver training when the explosion happened.
"A mortar round exploded in the mortar tub," said Brigade General James Lukeman. "We don't know yet what caused the malfunction."
"Accidents like these are very rare," said Stephen Ganyard, former Marine and ABC News consultant. "That said, anytime you are handling live material, the things you would actually go to war with, there's an inherent risk, a danger something could go terribly wrong."
President Obama continues to be briefed on the situation. More than a dozen military families are also learning their loved ones weren't injured in the battlefield, but here at home.
"The President's thoughts and prayers are with the families of those who were lost, and to those who are injured. We're monitoring the situation," said White House Press Secretary Jay Carney.
For years, units have traveled to the depot in the Nevada desert because of its remote location and terrain, which is comparable to the terrain in the Middle East. It spans 147,000 acres.
The site was established back in the 1930's to store Naval ammunition and later used to manufacture Naval ammunition in the 1970's.
Today, the depot also serves as an ammunition storage and disposal site for the military.
Military officials say a specific lot of mortars used in the accident have been suspended while the investigation continues.
Meanwhile, Nevada government leaders are commenting on the tragedy.
"I am deeply saddened to hear of the incident at the Hawthorne Army Depot this morning," Governor Brian Sandoval released in a statement. "The men and women who work and train there put service ahead of self each and every day. Our thoughts and prayers are with those who have been injured and we pray for their speedy recovery."
Note: Earlier reports stated that eight Marines were killed. The latest information from officials states that the number deceased is seven, not eight.
ABC News contributed to this report.