Two brush fires flared Wednesday, the first burning 300 acres and the second consuming 450 acres by nightfall.
A Camp Pendleton spokesman said investigators have not determined the cause of either blaze.
The first began at 12:45 p.m. at the southern end of the Marine Corps base near the San Luis Rey gate. By 2:30 p.m., the blaze was 80% contained, Sgt. Stan Pederson said.
The second fire, expected to be controlled by late Wednesday, ignited in brush near Vandegrift Boulevard. Pederson said the boulevard was closed because of smoke from Stuart Mesa Road to Wilcox Range Road, a distance of about 5 miles.