By Josh Edelson
Thousands of firefighters have been battling raging wildfires across swathes of parched California that forced residents to evacuate and shut miles of highway after claiming the life of a fireman.
Some 6000 homes were evacuated as 21 large fires burned in the bone-dry western US state, which is in the throes of a historic drought.
A total of 49,000 hectares of land have burned so far, according to figures provided by the state.
Dry lightning strikes sparked most of the fires, while the causes of others remained unknown. But authorities said they did not suspect foul play.
Thousands of lightning bolts since Thursday have caused hundreds of smaller fires throughout the state, but most of the blazes were concentrated in the north, California fire chiefs said.
About 9000 firefighters backed by helicopters and air tankers were battling the blazes, CAL FIRE spokeswoman Lynnette Round told AFP, with particular concern about the raging Rocky Fire in Lake County, northwest of the capital Sacramento.
"Our firefighters have been working extensively throughout the last two weeks, working hard to contain these fires. The weather has not been so kind," Round said.
"The dry, warm windy conditions then the dry lightning hitting, it just fuels those fires."
Stretches of Highway 20 were closed in both directions, spelling weekend travel misery for motorists.
Witnesses have described dramatic scenes as thick smoke from the giant fire turned day into night and flames swallowed up large tracts of woodland and forest.
Vehicles had been left to the flames, abandoned and burnt-out.
On Friday, California Governor Edmund Brown declared a state of emergency and the California National Guard was called in, underlining the scale of the threat facing the state.
Firefighter Dave Ruhl, 38, from South Dakota, was killed Thursday while fighting the Frog Fire in the Modoc National Forest outside Alturas.