Thousands of southern Californians abandoned their homes today as fire driven by the violent desert winds known as Santa Anas burned more than 50,000 acres and destroyed more then 300 homes in one of the most serious outbreaks in this fire-plagued region.

The winter rains are late and southern California is tinder-dry after almost six months without rain. The winds blow burning branches, leaves and shingles through the air, spreading the fire unpredictably, and firefighters said most of the seven separate blazes were burning out of control.

In San Bernardino County, where the fire pushed to the edge of the city of 112,000, fire caused four deaths and forced thousands to flee their homes.

Southern Californians have grown so accustomed to the fall fires that burn through their wind-tunnel canyons that they name them, much as the Atlantic and Gulf coasts name their hurricanes.One of them, named "Panorama" is the most devastating of the San Bernardino fires. It was set by arsonists, according to a California Department of Forestry Information spokesman. Incendiary devices were found on the scene.

Thousands of firefighters traveled from other counties and states to help fight the blazes, but their efforts were frustrated repeatedly by the high winds. San Bernardino Fire Chief Jerry Newcomb said that he had never seen winds so strong and that each time they shifted, they carried the flames into new areas.

Columns of smoke rose hundreds of feet into the air in places. In Los Angeles, where life went on undisturbed except for a litany of fire disaster reports on radio and television, a haze of smoke only slightly darkened a sunny blue-sky day.

In San Bernardino National Forest, a fire named "Sycamore" had burned 3,000 acres of brush and was growing, as was "Panorama," according to Dick Modee, a Forest Service spokesman.

Fire officials said the high winds made it impossible to fight some of the fires with water dropped from planes and helicopters.

In Malibu, a fire started in the same spot as a 1970 fire that caused millions of dollars of damage to the area's expensive homes. It was partly contained today, and fire officials hoped to gain full control over it if the wind there did not pick up again. About 2,600 acres of brush had burned after the fire was touched off by a downed power line, but there were no reports of property damage. Dick Friend of the Los Angeles County Fire Department said that most of what was burned was 20-year-old brush that had escaped the fires of 1970 and 1978.

Those were the worst recent fire years, but 1980 is bidding to join them. The fires raging this week started only eight days after about 50,000 acres were burned in the brushlands of Los Angeles, Orange, Riverside and San Diego counties. More than 60 homes were destroyed in those blazes.

One drama was played out at Mount Baldy Village, a town in San Bernardino County.Early Monday afternoon, an order came to evacuate the town as the "Thunder Mountain" fire was racing toward the village in the mountains 4,100 feet above sea level.

Few of the 800 permanent residents obeyed. Instead they stood with reporters and firefighters and watched the progress of the flames along a nearby ridgeline. So far the residents' gamble had not been lost.

June Mitchell, 24, one Mount Baldy resident who prepared to leave home, suffered a loss of another kind. "I was getting ready to split. I had packed all my belongings into my yellow Volkswagen ready to get out -- my skies, my books, my records, everything, even my two dogs and two cats. Then I went over to talk to some people. . . ." When she came back the car was gone. "Why would anyone steal a car with two dogs and two cats in it?" she asked tearfully.