San Francisco, Jul 11 (IANS): California Governor Jerry Brown has issued a state of emergency due to the effects of a wildfire that has caused the evacuation of thousands of residents.

As of Sunday, the Wall Fire swept through grassy foothills in the Sierra Nevada, about 60 97 km, north of state capital Sacramento, burned nearly 10 sq.km, forcing about 4,000 people to leave their homes and another 7,400 to prepare to evacuate, reports Xinhua news agency.

Governor Brown on Monday that extreme weather conditions and high temperatures have further increased the risk of fires; the circumstances of Wall Fire by reason of its magnitude are likely to be beyond the control of the services, personnel, equipment, and facilities of any single local government; and the California National Guard shall be mobilized to support disaster response and relief efforts.

Four firefighters were injured and at least 10 structures destroyed, the California Department of Forestry and Fire Protection, or Cal Fire, said.

As one of 14 wildfires across the Golden State that about 5,000 firefighters battled Sunday, the area burning was southeast of Oroville, the county seat of Butte in Northern California.

The fire broke out on Friday afternoon. While its cause is yet to be determined, the blaze was 20 per cent contained by Sunday. Cal Fire spokeswoman Mary Ann Aldrich acknowledged that the damage is expected to rise.