At least five spectacular fires spread through the drought-stricken suburbs of Los Angeles today, destroying more than 100 homes and blackening 30,000 acres of hillside in several communities.

"The flames came rolling down and burned expensive homes on both sides of the canyon," Los Angeles Fire Department spokesman Richard Friend said in describing the fire that struck the rustic, affluent suburb of Bradbury."The dry vegetation exploded in flames, which superheated the air and popped windows right out. When that happened, the homes were gone."

Fanned by 90 mph winds blowing in from the deserts to the east, the fires forced the predawn evacuation of the small community of Rancho Capistrano and torched no fewer than 75 homes -- some worth more than $1 million -- in Bradbury. Homes were destroyed in Duarte, Monrovia, Malibu, Sun Valley, Shadow Hills and Sunland. Tonight a fire burned along a ridge overlooking Burbank, threatening parts of that city.

A resident of Bradbury, 47-year-old John Hervey, suffered a fatal heart attack moving his possessions out of his home.

Many homes burned to the ground before firefighters and equipment could reach them. In some cases, firefighters watched helplessly as buildings burned because there was no water pressure.

Fire department officials suspected arson in at least two of the fires. In southern Riverside County near Lake Elsinore, where 12,000 acres of hillside were destroyed, county sheriff's deputies said they had an unidentified man in custody. In Bradbury, police said they arrested two people they said were looting the ruins of high-priced homes. That fire, too, was the apparent work of an arsonist.

Smoke and ash blown by the winds fell over much of the area, in some cases several miles from any of the fires.

"It looks like evening here. There's no sun to be seen," said William Baker of San Clemente, where the sky was darkened by smoke from a blaze 30 miles away.

A fire burned for a time at a canyon near the Pacific Palisades home where President-elect Ronald Reagan was working today. But fire officials said the blaze was contained and didn't threaten any homes there.

The other fires spread so quickly that firefighters had a hard time containing them. Because people were watering their lawns and homes to prevent them from catching fire, water pressure was so low that the firefighters' hoses could not douse some of the blazes. The high winds had knocked out power to booster pumping stations in the hilly areas. Water levels in the reservoirs in Los Angeles County were also at their lowest in almost six months, the last time southern California had a measurable rainfall.

"The ground and brush are extremely dry," said Dr. Morton Wurtele, a University of California at Los Angeles meteorologist. "The entire countryside around Los Angeles is a fire hazard."

Wurtele blamed the rapid spread of the fires on the infamous Santa Ana winds, which blow in every autumn from the deserts east of Los Angeles and reach near-hurricane speeds in the thousands of canyons that cut through the hills of Los Angeles County. Wind gusts of 80 to 90 miles an hour were routinely recorded in the canyons the last two days.

"The wind is everywhere," Wurtele said. "All the firefighters can do in a situation like this is conduct a holding operation."

Wurtele said the winds coming out of the deserts are so dry they desiccate the vegetation on the hillsides even more than the lack of rain. He said the Santa Ana winds of the last two days dried out the air around Los Angeles to near-record lows for humidity.

A high-pressure region over the Great Basin in Nevada and northern Arizona has driven dry desert air into southern California, where the prevailing winds normally blow cool air in from the Pacific Ocean.The desert winds are compressed as they reach the lower elevations near Los Angeles, which forces them to higher speeds and raises their temperature. The high pressure behind the winds pushes the air even faster through the canyons, where the fires were at their worst.

"Burning embers can jump right over hills near the canyons," Wurtele said. "It's not uncommon to see fires skip from one place to another when those desert winds are blowing."

In knocking down power lines, the winds started new blazes in some places and brought scattered power outages throughout the area.

So fierce were today's fires that the smoke plumes were visible in satellite photographs sent back to earth from 22,400 miles in space.

The 5,000-acre fire that hit Bradbury in the San Gabriel foothills near Pasadena caused the most property damage. The fire destroyed the $500,000 art collection of a man named C. B. Stratton and six uninsured race cars worth more than $500,000 belonging to racing driver Mickey Thompson.

"The fire burned the coat right off my back," said Thompson, who drove a burning propane truck away from his house. "I had to crash it [the truck] through two burning gates. Just as I jumped out, it exploded. It blew me plumb up the side of the hill."