San Diego's Qualcomm Stadium, which sheltered 10,000 people at the height of the disaster, has now been closed as people return to what remains of their homes.

American border patrol agents discovered four charred bodies in rugged mountains near the Mexican border, bringing the probable death toll from California's bushfires to 12, even as firefighters gained the upper hand in their five-day battle.

Agents found the burned remains of three males and a female in the mountains east of San Diego, about 16 kilometres west of the Mexican border town of Tecate.

They were thought to have died in the Harris fire, US Border Patrol spokesman Matthew Johnson said.

"It seems fire-related. The Harris fire at the border was out there," Mr Johnson said. The victims, he added, would be turned over to local authorities for identification and further investigation.

The discovery has prompted US authorities to urge illegal immigrants from Mexico not to attempt crossing into California.

According to the San Diego-based "Angeles de la frontera" (Angels of the Border), hundreds of Mexicans have sought to cross the border during the crisis, believing that authorities will be distracted by the fires.

"Hundreds of people have tried to cross and we've begged them not to," said Enrique Morones, a spokesman for the group, which works to provide assistance to immigrants making the trek through the desert into the US.

"We have launched an appeal for people to stop trying to cross the border, because there is a very real risk it will cost them lives," added Alberto Lozano, a spokesman for the Mexico Consulate in San Diego.

The wildfire crisis in California has led to the redeployment of 200 National Guard soldiers from the border to the fire zones, a decision which may have tempted immigrants to try their luck at crossing, Mr Morones said.

"We think this week that the people-smugglers have convinced people to try and cross the border from the canyons and mountains to the north of San Diego," Mr Morones said.

As crews used a break in the weather to bring most of the fires under control, President George W Bush surveyed the devastated areas and met with a few of of the estimated 500,000 people who fled their homes in California's largest mass evacuation.

President Bush, who was roundly criticised for his handling of Hurricane Katrina in 2005, flew over hard-hit San Diego in a helicopter with California Governor Arnold Schwarzenegger and visited charred neighbourhoods.

"It really is important for me to come out here and see firsthand the situation, and there's no question a lot of people are suffering, and there's no question there's been terrible losses," Mr Bush said. © 2007 Australian Broadcasting Corporation