Fire burning off of Highway 166 in Carrizo back country

A brush fire has burned at least 400 acres as of 1:15 p.m. Saturday near Highway 166 and Cottonwood Canyon in the area straddling the San Luis Obispo and Santa Barbara county line, according to County/Cal Fire.

About 80 firefighters are battling the blaze, which is burning into the Carrizo Plain National Monument.

The area is about 30 miles east of Nipomo and northeast of Santa Maria.

It was reported about 9:20 a.m., when five acres initially burned and spread slowly into the canyons, Cal Fire reported.

The cause of the fire is still being investigated.