Fueled by strong winds, wildfires have killed two people in parts of Southern California, authorities said on Tuesday.

An air tanker makes a drop ahead of the wildfire burning over Porter Ranch in California October 13, 2008. [Xinhua/Reuters Photo]

The fires have also charred more than 20 square miles (32 square kilometers) of land in suburban Los Angeles and northern San Diego County in three days, with the fiercest blazes burning in the San Fernando Valley near Los Angeles, firefighters said.

Intense winds caused a fire in the west end of the valley to double in size from 5,000 to nearly 10,000 acres overnight, fire officials said.

A second fire at the northeast end of the valley was 70 percent contained on Tuesday, Inspector Paul Hartwell said. Officials reduced the acreage to 4,800 acres from 5,300 acres.

About 3,000 homes remain evacuated and winds could return in the afternoon, Hartwell said.

The fire, which broke out near the U.S.-Mexico border in San Diego County Tuesday morning, has forced the evacuation of about 300 homes in the town of Campo, said Sheriff's Lt. Anthony Ray.

It had burned about 150 acres but no structures have been burned and no one has been injured, Ray said.

More than 2,000 firefighters from several fire departments in Southern California and elsewhere in the state were assigned to fight the fires, with additional personnel and equipment being requested as needed, the Forest Service reported.

Governor Arnold Schwarzenegger has declared a state of emergency in the fire-stricken areas and urged residents to be prepared for anything.

"Winds are causing fire conditions to change by the hour, which is why it is so important that residents in the areas surrounding these wildfires heed warnings from public safety officials to evacuate," Schwarzenegger said.