Los Angeles: Four burned bodies found in the path of California's fierce wildfires raised the death toll to at least 12 people, with over 60 injured, as officials turned towards assessing the damage on Friday.

Border patrol agents discovered four charred bodies in mountains near the Mexican border. The victims are thought to be illegal immigrants overrun by flames as they walked through the rugged terrain.

Agents found the remains, believed to be of three men and a woman, at the bottom of a rocky ravine east of San Diego and about 3 miles from the Mexican border.

Although over 20 fires raged across Southern California into a sixth day, some 8,000 firefighters had brought most of them under control and no more homes were in imminent danger.

As officials began the massive clean-up and recovery operation, a risk firm said insured losses would likely be $900 million to $1.6 billion. Hot, dry winds had whipped up the string of fires but up to three are being treated as arson.

Some lost everything to the flames but most of the 500,000 people forced to flee in California's largest evacuation were expected to be back in their homes by the weekend.