Lowe Lake - Blazes raging in forests and woodlands across California have taken the life of a firefighter, burned two dozen homes and forced thousands of people to flee as crews continue to battle the flames from the air and the ground.Twenty-one large fires, many sparked by lightning strikes, were burning across Northern California on Saturday, said Daniel Berlant, spokesperson for the state Department of Forestry and Fire Protection. About 8 000 firefighters were working to subdue them, something made incredibly difficult by several years of drought that have dried out California.The fires prompted Gov. Jerry Brown to declare a state of emergency for California and activate the California National Guard to help with disaster recovery.Berlant said the danger was expected to continue through the weekend, with more thunderstorms expected.Firefighter killedEngine Capt. David Ruhl, from South Dakota, was killed battling a fast-moving blaze that broke out on Thursday in the Modoc National Forest about 100 miles south of Oregon.Ruhl was in a vehicle on Thursday, looking for ways to fight the blaze, when officials lost contact with him, fire information officer Ken Sandusky said. His body was recovered on Friday.Ruhl, part of a Black Hills National Forest firefighting team, had been helping California firefighters since June.The fire had grown to about 3 acres by Saturday, and it was 5% contained.Burning hillsThe biggest fire was in the Lower Lake area north of San Francisco, where firefighters had to wade through thick smoke and flying embers to turn loose horses, goats and other livestock as their owners fled to safety.The fast-moving fire had burned 24 homes and 26 outbuildings by Saturday night and more than 6 000 other homes were threatened. Mandatory evacuations were expanded to include more than 12 000 people in sweeping areas of ranches and small rural communities.Only 5% contained by Saturday, the fire had charred 110 square kilometers, raging in hills covered in dense brush and oak trees.Throughout the day, fingers of flame - some over 30 meters high - moved several miles north and east, state fire spokesperson Ron Oatman said.Foothills firesA woman was arrested in connection with a small fire near Groveland, a stop-off point for travelers headed to Yosemite National Park.The 80-hectare fire, about 30 km from the park's entrance, was 80% contained on Saturday, when all evacuations were lifted and residents were allowed to return to their homes.Lisa Ann Vilmur was arrested on Thursday night on allegations of recklessly causing a fire. She was jailed on $100 000 bail, and it wasn't known if she has an attorney who could comment.In a separate foothills blaze northeast of Sacramento, evacuation orders were lifted for residents of 50 homes. The fire, which ignited on Saturday, destroyed two homes, but was almost fully contained.Bass Lake blazeA wildfire that caused the evacuation of 200 homes in the central California community of Cascadel Woods was 50% contained.Authorities say a boy acknowledged starting the fire near Bass Lake by playing with a lighter to burn pine needles. The fire, which has been burning for several days, has grown to nearly 20 square kilometers.Napa fire lines holdingCrews battling a fire east of Napa Valley held their ground on Saturday, more than a week after the blaze started about 70 km east of Napa's wine county.More than 30 square kilometers in Solano County have been charred, but the fire was 95% contained, and crews expected to have it fully corralled by Monday.