Crews are battling a 150-acre wildfire that started on the Camp Pendleton Marine Base and has burned into the Cleveland National Forest.
Marine officials say no injuries have been reported and no structures are threatened.
The fire broke out shortly after 4 p.m. Wednesday and is chewing through grass and brush. It has moved northward from the Marine base into the forest's San Mateo Canyon area.
The cause of the fire has not been determined. Crews from the base and the United States Forest Service will continue to battle the flames throughout the night.
Camp Pendleton is in northern San Diego County.