A fast-spreading wildfire in Northern California's Lake County has destroyed two buildings and more than doubled in size overnight.
A Cal Fire spokeswoman said the fire broke out Wednesday afternoon and is threatening dozens of buildings. At least 500 people are being forced to evacuate as the blaze rages and fire crews from Sonoma, Lake and Napa counties join the fire lines.
The fire grew more than 7.5 square miles overnight and has now charred more than 12 square miles. It was not contained at all Thursday morning.
Cal Fire said it traveled at a rapid rate because the hard-to-access terrain is heavy with brush and timber in Lake County.
Evacuation centers have been set up in Middleton and Clearlake and an animal evacuation center has opened at the Lower Lake Social Services parking lot.
Meanwhile, crews battling a fire east of California's Napa Valley held their ground, keeping that blaze from jumping any more containment lines, fire officials said.
The fire, which has burned for more than a week, has charred more than 11 square miles in Solano County. It jumped the containment line Tuesday in rugged, steep terrain baked by triple-digit temperatures.
"We're optimistic that we are able to stop and hold it," said Daniel Berlant, a spokesman for the California Department of Fire and Forestry Protection.
At least 136 structures remain threatened, and more than 200 people were still under orders to evacuate their homes on Wednesday. It is 80 percent contained.
Temperatures were expected to remain high until Friday, when storms moving into Northern California could bring cooler weather but also a threat of lightning, Berlant said.
Elsewhere, in the Sierra Nevada foothills, evacuation orders have been lifted for residents of 50 homes after a fire started there Saturday, Berlant said.
The fire northeast of Sacramento burned through more than 3 1/2 square miles and is about half contained.
Residents in the Central California community of Cascadel Woods north of Fresno were being warned to prepare to evacuate because of another blaze that has charred more than 3 square miles. It is 30 percent contained.
Authorities say a boy acknowledged starting the Cascadel Woods fire by playing with a lighter to burn pine needles in the dry Sierra Nevada. The boy faces criminal charges but remains out of custody because he and his family are cooperating, officials say.
In Shasta County in the far northern part of the state, firefighters were battling two fires that have prompted some evacuations and several road closures.
And in Butte County, the growing Swedes Fire was burning over a square mile near Bangor but was threatening 50 buildings and was just 10 percent contained early Thursday, according to Cal Fire.