So far at least four people were reported to have died with over 50 injured in one of the region's worst blazes since 2003, media said.
A total of 21 fires have destroyed some 1,800 buildings and over 1,100 square kilometers (683 miles) of forest, with the county of San Diego being the worst hit with over 300,000 people alone being evacuated from their homes. Food and aid is being distributed among those affected.
President George W. Bush has canceled his trip to St. Louis, Missouri, and scheduled a visit to the disaster-hit region on Thursday.
Governor Arnold Schwarzenegger declared a state of emergency in seven counties on Tuesday, saying the fires represented a "tragic time" for California.
A total of 90 firefighting aircraft, 1,500 National Guard troops, and 6,000 firefighting crews are engaged in the operation.
Also hit by the fires is the prestigious area of Malibu, where many celebrities have their homes, including actor Mel Gibson and musician Sting.
In October 2003, fires in California claimed the lives of dozens of people, destroyed 3,000 buildings, causing some $1 billion in damage.
