A massive wildfire has destroyed scores of buildings and threatens to raze several vineyards in California, where a prolonged drought has left vegetation tinder-dry, officials warned Tuesday.

   The Soberanes fire, in the coastal Big Sur   tourism hotspot, has 

incinerated 105 square miles (270 square kilometers) of the Los Padres National Forest since it started more than two weeks ago.

Some 5,000 firefighters are battling the blaze, which is just 50 percent contained, Rigoberto Herrera of the California Department of Forestry and Fire Protection (CalFire) told AFP.

The mountainous terrain in northern California has made the job particularly difficult, and the flames have destroyed 57 buildings with another 410 under threat, causing hundreds of homeowners to evacuate.

A bulldozer driver died battling the flames, said CalFire, while four vineyards under threat, according to Kim Stemler of the Monterey County Vintners and Growers Association.

Investigations into the cause of the blaze are under way, although a camp fire is suspected of being the source.

Further south, the Pilot fire in San Bernardino county has doubled in size in just 24 hours to 11 square miles, while blazes in Colorado's Routt national forest and Boise, Idaho have consumed more than 150 square miles between them.

Robyn Broyles, of the National Interagency Fire Center, said the rest of the country was faring rather better than in previous years, however.

"Last year at the same time we'd already had 37,693 fires, compared with 35,646 this year, and in terms of area burned, it's half," she told AFP.

The statistics are skewed however by giant fires that were left to burn last year in vast, sparsely populated parts of Alaska.