A brush fire that started on Camp Pendleton yesterday afternoon had grown to 125 acres and was burning last night in the Cleveland National Forest, fire officials said.

U.S. Forest Service personnel have taken charge of the firefighting effort, with Cal Fire and Camp Pendleton crews offering assistance.

Five engines, seven fire crews, two bulldozers, three tanker airplanes and three helicopters were fighting the blaze, called the Yankee fire. The flames were burning into steep, rugged terrain near San Mateo Canyon, but no structures were threatened.

Officials have not determined what sparked the blaze, which was reported just after 4 p.m. –J.L.J.