US President George W Bush is preparing to visit fire-ravaged southern California.

Mr Bush declared a "major disaster" in seven Southern California counties which means extra federal help will be available.

At least 15 separate blazes are still burning out of control and well over 1,500 homes have been destroyed.

The wildfires have forced as many as one million people to flee their homes in what is the biggest evacuation in the state's modern history.

San Diego has been hit the hardest, and officials there put losses in excess of $1 billion (£488m).

Dying winds gave California firefighters their first big break on Wednesday after four days of battling the blazes, but San Diego faced more calamity as fires there burned out of control.

The skies over much of the region were filled with thick, acrid smoke, forcing residents to stay indoors or wear masks.

Governor Arnold Schwarzenegger said 18 fires threatened 25,000 structures, and 8,900 firefighters remained on the fire lines.

Six deaths have been reported, while 40 people suffered injuries, many of them firefighters.

San Diego, state and federal authorities set up food, shelter and medical services for the displaced, amid sharp memories of the debacle following Hurricane Katrina in New Orleans.

Fourteen thousand evacuees are now being housed at San Diego's Qualcomm Stadium.

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