A plume of smoke rises from the brush fire at Camp Pendleton. Courtesy OnScene.TV

A brush fire spread over swaths of open terrain on the grounds of Camp Pendleton on Friday afternoon.

The blaze broke out for unknown reasons in the northern reaches of the military installation near the Fallbrook Naval Magazine area, according to Cal Fire, which sent crews to help Marine Corps personnel extinguish the flames.

By 5 p.m., the fire had blackened roughly 30 acres, but was not posing any structural threats, the state agency reported.

—City News Service