8 U.S. Marines missing, 1 dead in accident off California coast

One Marine has died, two were injured and eight others were missing after an amphibious assault vehicle accident off the coast of southern California, the Marines said early Friday.

The accident happened Thursday and search and rescue efforts were underway Friday morning with support from the Navy and Coast Guard, the Marines said in a tweet.

All of the Marines involved were assigned to the 15th Marine Expeditionary Unit, which is based out of Camp Pendleton in San Diego County.

"We are deeply saddened by this tragic incident. I ask that you keep our Marines, Sailors, and their families in your prayers as we continue our search," Col. Christopher Bronzi, the unit's commanding officer, said in another tweet from the Marines.

The Marine Expeditionary Force is the Marine Corps' main war-fighting organization. There are three such groups, which are made up of ground, air and logistics forces.