Relentless wildfires forcing the largest evacuations in California's modern history raged into a fourth day on Wednesday as 10,000 exhausted firefighters hoped for a break in the hot winds whipping the flames.

With half a million people driven from their homes, 1,000 houses already lost and some 470 square miles scorched across the southern half of the state, Gov. Arnold Schwarzenegger's government has put economic losses in the hundreds of millions of dollars.

"If the weather cooperates maybe we can turn the tide," U.S. Homeland Security Secretary Michael Chertoff said as he toured San Diego's Qualcomm Stadium, where 10,000 people have taken refuge. "We're still facing some very serious fires."

Weather forecasters say fierce Santa Ana winds blowing in from the desert should begin to subside by Wednesday afternoon.

A drop in the winds, which can howl at gale forces through Southern California's mountain passes and canyons, would also allow for lower temperatures and higher humidity, which could prove crucial in fighting more than a dozen wildfires still burning out of control.

In the San Diego area in the south, firefighters were struggling with four major fires that have forced 500,000 people into the largest evacuation in the state's recorded history.

"I'm worried for my baby, my house, my kids, everything," said Ana Ramirez, 30 and pregnant, who was taking shelter at the stadium with her 4-year-old daughter.

Most of the destroyed homes were in the San Diego area, where one person was killed on Sunday. Four other deaths were reported among the evacuees and more than three dozen people have been injured, including 18 firefighters.

Fires also burned on the outskirts of the Mexican city of Tijuana, 20 miles from San Diego.

'MAJOR DISASTER'

Schwarzenegger asked President George W. Bush to upgrade California's wildfires to a "major disaster," which would trigger federal help.

Bush had issued a declaration of emergency on Tuesday and plans to visit the fire-stricken area on Thursday.

But in a new letter, Schwarzenegger told Bush "this disaster is of such severity and magnitude that effective response is beyond the capability of the state and local governments."

Schwarzenegger said 68,000 homes, from cabins to luxury villas, were threatened across the state and that 10,000 men and women were working the fire lines against flames shooting as high as 100 feet.

There were some signs of progress as crews largely contained a fire in the hills above the seaside enclave of Malibu, allowing residents to return. Some San Diego evacuees were allowed back to their neighborhoods late on Tuesday.

Those taking shelter at the stadium, including senior citizens from nursing homes, called it well organized and clean -- in contrast to the chaos at the Superdome in New Orleans, a refuge for thousands of people after Hurricane Katrina hit the Gulf Coast in 2005.

Paul Fiest, a spokesman for California's Office of Emergency Services, said the state had not seen such a large evacuation at least since 1917, the earliest date that records were kept.

(Additional reporting by Dan Whitcomb in Los Angeles)

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