A wildfire spread through 250 acres of rugged Southern California wilderness Monday, but no homes were threatened.

Some 300 firefighters, aided by helicopters and aircraft, had the flames 10 percent contained by evening, and the fire was expected to be fully surrounded sometime Tuesday, said Battalion Chief Kris Concepcion of the Orange County Fire Authority.

The fire was about 2 1/2 miles from any structures, he said, adding that the aircraft would not be flying overnight.

Flames were reported at 11:30 a.m. about a dozen miles northeast of San Juan Capistrano and climbed rapidly up steep terrain near the Ortega Highway, a major connector between Orange and Riverside counties.

Authorities said a disking operation for clearing brush or breaking ground for agricultural use caused a power pole to fall. Disking usually involves a tractor pulling a device.

Weather was dry, but there was little wind during the day. Concepcion said humidity was expected to rise to 30 percent overnight.