Seven Marines were killed in an explosion during a Marine Corps training exercise at Hawthorne Army Depot in western Nevada , the Marine Corps said Tuesday . Eight others were injured . The cause of the Monday night blast was a 60 mm round that detonated inside a mortar tube , Brig . Gen. James W. Lukeman , commanding general of the 2nd Marine Division , told reporters . The Marines said in a statement Tuesday evening that all 60 mm mortar rounds and tubes used to fire them are being pulled pending an investigation . One Marine and one sailor suffered very serious injuries , and four Marines are in serious condition , the service said in a news release . Another Marine was treated and released . One Marine suffered minor injuries , but it is unclear whether that individual was hospitalized . `` Let me say to the families of our Marines and sailors that our hearts go out to you , '' said the general , whose division is based at Camp Lejeune in North Carolina . `` We appreciate your sacrifice , and we 'll do all that we can to continue to support you . '' The Marines will release the names of the deceased 24 hours after their relatives have been notified . Lukeman would n't give any details about which Marine unit was involved but said it was involved into a mountain training exercise that involved live ammunition . Marines had been training at Hawthorne and the nearby Marine mountain warfare training center in Bridgeport , California , for about a month . Senate Majority Leader Harry Reid , who represents Nevada , called it `` quite a big explosion '' and said the area of the blast was cordoned off as details emerged . `` We do n't know exactly what happened , but it was a violent explosion , we know that , '' he said . `` Our thoughts are with those who were injured and , of course , the families of those who lost loved ones . '' 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 . KOLO : Seven Marines dead in Hawthorne explosion . President Barack Obama was immediately made aware of the incident , and the White House was monitoring the situation , spokesman Jay Carney said . `` We are obviously in the early stages of assessing the incident , '' he said . `` It is a tragedy , clearly . ''
Marine say Seven people suffered very serious wounds . Marines temporarily discontinue use of type of mortar round that caused explosion . Unit was undergoing a live fire exercise at a mountain warfare training center . KOLO is 60 mm southeast of Nevada , Nevada .