
A fast-spreading wildfire in Northern California's Lake County has destroyed two buildings and more than doubled in size overnight all because a boy was playing with a lighter in the Cascadel Woods, say authorities.

Authorities say a boy acknowledged starting the Cascadel Woods fire by burning 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.

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.

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Flames leap up on a ridge around Lower Lake, California, where 600 firefighters are trying desperately to extinguish a wildfire

Thousands of acres - including this fenced-off land in Lake County, California - have been consumed by the spreading flames

The Arrowhead Hotshots conduct firing operation near a structure threatened by the Rocky Fire near Clear Lake Wildfires in California on Wednesday. Authorities say the blaze was all started by a boy who

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 1/2 square miles overnight and has now charred more than 12 square miles. It was not contained at all Thursday in the morning

A crew member of the Arrowhead Hotshots listens to his radio while conducting a firing operation near a structure threatened by the Rocky Fire near Clear Lake Wildfires in California

The fire grew more than 7 1/2 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.

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

Exhausted firefighters pause from their work in Lower Lake as smoke and flames billow into the sky not far away

A spot fire which sprang up on this farmland starts to spread, threatening first agricultural buildings then a house further away

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.

Firefighters from California watch a firing operation at the Rocky Fire Wildfires. Elsewhere, in the Sierra Nevada foothills, evacuation orders have been lifted for residents of 50 homes after a fire started there Saturday

Smoke rises above the landscape as the Rocky Fire continues to burn at sunset on Wednesday. The boy who allegedly started the fire afces charges but will not be placed in custody because he and his family are cooperating with the authorities

Flames consume the landscape at the Rocky Fire. Cal Fire said it traveled at a rapid rate because the hard-to-access terrain is heavy with brush and timber in Lake County

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.

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.

A wall of flames lurches over a ridge as a resident of Morgan Valley Road near Lower Lake prepares to evacuate because of the fire

An air tanker drops retardant at the Rocky Fire as the wind picks up spreading the flames south down in the Morgan Valley during sunset

A Cal Fire strike crew prepares to make a cut line at the Rocky Fire near Lower Lake California on Friday

A firefighter douses a burning mobile home in Isleton, California, as other homes around it were consumed

Other firefighters are picked tending to the hot wreckage at the Isleton settlement