Four U.S. Marines were killed at Camp Pendleton during a range maintenance operation Wednesday morning.

The deadly incident happened around 11 a.m., according to a statement just released by the base. Few details have been released on what occurred, but officials said the Marines' identities will be made public after their families have been notified.

"We offer our heartfelt prayers and condolences to the families of the Marines lost today in this tragic accident. Our first priority is to provide the families with the support they need during this difficult time," Brig. Gen. John W. Bullard said in a statement.

The deaths come eight months after a mortar explosion killed seven Marines during an exercise in Nevada. The cause of this morning's accident is currently under investigation.

