CORRECTION: Southern California burns as 500,000 flee

(Corrects number of homes threatened to 68,000, from 6,800, 5th paragraph)

By Dana Ford

SAN DIEGO (Reuters) - Towering wildfires burned out of control across Southern California for a third day on Tuesday as 500,000 people fled the San Diego area and firefighters made a desperate stand to save a mountain town ringed by flames.

More than a dozen fires blazed from the horse country north of Los Angeles to the Mexican border 150 miles south, torching more than 1,500 houses and other buildings, blotting out the sun with smoke and raining ash on the streets.

Most of the destroyed homes were in the southern end of the state near San Diego, where three major wildfires burned unchecked and half a million people were ordered to evacuate to beat the flames, some 8,000 taking refuge in a football stadium.

Two deaths have been reported and more than three dozen had been injured, including 18 firefighters.

As the firestorms raged, Gov. Arnold Schwarzenegger said 68,000 homes were threatened statewide and 6,000 men and women were manning the fire lines, sometimes hunkering down in fire shelters when shifting winds trapped them.

"We have had three things come together -- very dry areas, very hot weather and a lot of wind. This makes the perfect storm for fire," Schwarzenegger said at Lake Arrowhead, where blazes threatened two nearby mountain communities.

Both Schwarzenegger and San Diego Mayor Jerry Sanders put the number of evacuees at half a million.