First Lt. Colleen McFadden says the rollover happened last afternoon.
McFadden says the Marine was from the 1st Marine Division, and the person's name will not be released until 24 hours after relatives are notified.
Other details including the type of vehicle and the extent of the injuries were not immediately released.
McFadden says "we want to ensure the Marines and their family members are being provided for during this difficult time."
The accident happened at Camp Pendleton, a vast seaside base north of San Diego that is the major West Coast outpost for the US Marine Corps.