A wildfire burning in Southern California's rugged San Bernardino Mountains has grown to more than 12 square miles, but it hasn't reached any of the homes it has been threatening.

Prospects for late Tuesday into Wednesday looked good for firefighters who had the blaze just 6 percent contained, with temperatures dipping into the low 60s and humidity rising.

Mandatory and voluntary evacuations covered 5,300 homes in the Southern California fire area between mountain communities around Lake Arrowhead and the high desert city of Hesperia to the north, said Lyn Sieliet, a U.S. Forest Service spokeswoman. The number of people who left was not known.

More than 900 firefighters aided by retardant-dropping air tankers and water-dropping helicopters took on the blaze that erupted Sunday. The cause remained under investigation.

Meanwhile, California's biggest wildfire expanded to more than 104 square miles north of scenic Big Sur.

An army of more than 5,000 firefighters and a fleet of air tankers and helicopters made progress, however, surrounding 50 percent of the nearly 3-week-old fire.

Some residents have been allowed to return to their homes, but some evacuation orders remained in place, while others were reduced to warnings.

Five state parks on Highway 1 between San Francisco and Los Angeles remained closed.

The fire, which has destroyed 57 homes, damaged three others and led to the death of a bulldozer operator in an accident, was caused by an illegal campfire.