BONNY DOON - The Lockheed Fire consumed 2,800 acres in the remote forest between Swanton and Bonny Doon on Thursday as quick-moving flames fueled by thick underbrush raged out of control for a second day, leading authorities to order the evacuation of up to 2,400 residents.

Bolstered by 120 engines and 20 aircraft, more than 2,000 firefighters serving in ground crews employed bulldozers, axes and bare hands to set backfires, lay hose lines and dig breaks in an attempt to contain the blaze, which raged in a parched expanse of tinder-dry brush and timber that hasn't burned for more than six decades.

Cal Fire said the blaze started near the Lehi Camp, a Mormon retreat at the top of Empire Grade, and the Lockheed Martin facility. The cause is unknown.

Just five years ago, Cal Fire identified the largely inaccessible woodlands surrounding the two sites as the county's worst wildfire hazard. The last major blaze in that area, the 19,000-acre Pine Mountain Fire of 1948, which burned for a month, is still the county's largest wildfire on record.