FIREFIGHTERS are finally making progress in the titanic task of cutting fire lines around one of the biggest blazes in California history.

As the blaze straddling Santa Barbara and Ventura counties entered its 10th day, crews had carved containment lines around a quarter of it.

But the wildfire still raged on Tuesday, threatening thousands of homes and stranding tens of thousands of evacuees.

The so-called Thomas fire, one of several around the state, has burned more than 900 structures, at least 700 of them homes. And it has stretched across nearly 370 square miles (958 sq km) of territory, making it the fifth largest in state history.

Elsewhere, fire officials announced that a cooking fire at a homeless encampment sparked a blaze last week that destroyed six homes in the Bel Air neighbourhood of Los Angeles.

Arson investigators determined that the so-called Skirball fire near the world-famous Getty museum was started by an illegal fire.

The camp was empty when firefighters found it but people had apparently been sleeping and cooking there for at least several days. Back at the largest of the wildfires, firefighters protected foothill homes while the blaze grew mostly into forest land, Santa Barbara County Fire Department spokesman Mike Eliason said.