Update 10:20 p.m. EDT: An eighth Marine has died.

A Veterans of Foreign Wars official told KAKE-TV that an eighth Marine has died after a mortar shell explosion during mountain warfare training in Nevada's high desert.

John Stroud, national junior vice commander in chief for the VWF, began a memorial event near the site of the blast by saying "one of the critical has passed."

Mourners then laid eight floral arrangements at a park near the Hawthorne Army Depot.

Stroud says he spoke with Marine officers who gave him the news before Tuesday night's ceremon

At least seven United States Marines were killed and seven were wounded at the Hawthorne Army Depot in Nevada on Monday when a mortar exploded during an overnight training exercise.

According to NBC News, accounts conflict about how the Marines were killed. One report alleges that they were killed when a 60-millimeter mortal shell they were loading exploded in a tube. But another account said the shell exploded even before it was loaded, just as the Marines were picking it up.

Military officials said that four of the Marines were immediately killed during the explosion, while two others died waiting to be transported to the hospital.

The injured Marines were flown to two different hospitals: eight are currently being treated at Renown Regional Medical Center, a Level II trauma center approximately 100 miles away from the military storage and training facility.

Stacy Kendall, a spokesperson for the hospital, said that of the eight Marines treated for trauma and fractures, three were in serious condition and five were in fair condition.

According to the website for the Hawthorne Army Depot, the facility is “an archive site for storing slow-moving ammunition and stocks awaiting demilitarization,” and is used as a training ground for Special Operations forces scheduled to be deployed to the Middle East.

“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,” Maj. Gen. Raymond C. Fox, the division's Commanding General said. “We mourn their loss, and it is with heavy hearts we remember their courage and sacrifice.”

A spokesperson for the Marines said that the accident is being investigated and that the military will identify the fatalities 24 hours after notifying their families.