Four U.S. marines were killed Wednesday in a training accident at Camp Pendleton in Southern California.

Authorities said the tragic accident occurred at 11.a.m. PST. A U.S. military official told NBC San Diego that the incident involved detonation of unexploded ordnance on a range at the base.

According to Reuters, a spokesman said the four marines killed at Camp Pendleton were "clearing an area of obstructions" when the accident occurred.

The identities of the four marines killed in the accident will be released after their families are notified.

Brig. Gen. John W. Bullard, Commanding General, Marine Corps Installations West - Marine Corps Base Camp Pendleton issued the following statement:

"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."