The seven Marines were working on range area known as John W. Bullard used for live-fire drills . But the deaths did n't occur under such live fire , a military source says . `` We offer our heartfelt prayers and condolences to the families of the Marines lost today in this tragic accident . It 's possible that unexploded ordnance suddenly detonated , the source says . In this week , seven Marines were killed when a mortar round exploded in California .
The seven Marines were working on range area known as John W. Bullard used for live-fire drills . But the deaths did n't occur under such live fire , a military source says . It 's possible that unexploded ordnance suddenly detonated , the source says . In this week , seven Marines were killed when a mortar round exploded in California .