Lance Cpl. William T. Wild IV: In October 2010, the Anne Arundel, Md., resident joined the Marines. By December 2011, the mortarman had earned his new rank, and he also earned a number of recognitions, such as the Combat Action Ribbon and Global War on Terrorism Expeditionary Medal. He was 21.

Authorities still don't know how the men died. McNulty said Wednesday they know only that the "60 mm mortar system failed to function as designed," and are trying to find out why.

Hawthorne Army Depot, about 140 miles southeast of Reno, is used for storing ammunition and weapon stocks awaiting demilitarization. The facility also provides high-desert training facilities for military units.

The night after the incident, the Marines issued a statement saying that 60 mm mortar rounds and tubes used to fire them are being pulled pending the investigation.

In addition to the dead, eight service members were injured in the explosion. The Wednesday night update from the Marines indicates that a Navy Corpsman remains "very seriously injured," while five others are "seriously injured." Two Marines have been treated for minor injuries and released.