Thousands of federal, state and local firefighters are feverishly attacking six major wildfires in central and far northern California, four of which grew rapidly overnight and prompted evacuations of homes, vacation cabins and recreation areas.
CalFire spokesman Dennis Mathisen says the scope and intensity of the blazes burning Saturday, three of them sparked by dry lightning, are comparable to the fire activity California doesn't usually see until September.
Mathisen says the only silver lining is that the fires are mostly located in forests and sparsely population rural areas, so fewer homes are threatened and fewer people have had to evacuate.
One of the most serious was burning in Modoc County near the community of Day. It started Wednesday and had torched nearly 19.5 square miles by Saturday morning. A community of 150 homes called Lookout Ranchettes is under evacuation.
California is in its third year of drought, which has heightened the fire danger.
The California Governor's Office of Emergency Services announced Friday that it has asked the state's National Guard to activate specially trained helicopter units to help fire agencies.
"The forward deployment of these will help incident commanders and the personnel they are directing save lives, homes and personal property as well as valuable watershed by providing critical resources within a moment's notice,'' California emergency services Director Mark Ghilarducci said in a statement.
In Yosemite National Park, residents from about 50 homes were allowed to return home Friday afternoon. They were the last remaining evacuees from a fire that had burned through 6 1/2 square miles and destroyed a home and a duplex. It was 58 percent contained.
The fire was burning close to one of the park's three treasured stands of giant sequoia trees, and officials said crews were trying to shore up containment lines.
The park remained open and was largely unaffected.
The causes of the Yosemite and Sierra fires were not known.