California fire sends 20,000 fleeing, burns 75 homes

* Wildfire menaces Santa Barbara proper

* Wind-driven flames consume 3,500 acres (1,400 hectares)

* 3,500 homes, 100 businesses in immediate jeopardy

SANTA BARBARA, Calif., May 8 (Reuters) - A stubborn brush fire that consumed 75 foothill homes above the coastal town of Santa Barbara raged with renewed ferocity for a fourth day on Friday, forcing at least 20,000 people to flee as it advanced on the city and two nearby communities.

The conflagration, marking the fourth wildfire to strike the affluent, picturesque Santa Barbara area in two years, had charred some 3,500 acres (1,400 hectares) by daybreak after a night of hot, dry erratic winds that drove flames across a highway and through more homes.

"Literally, last night, all hell broke loose," city Fire Chief Andrew DiMizio told reporters. "We saw the fire spread laterally across the top of the city and the fire front extend to almost 5 miles (8 km) now."

He said fire crews fought a heroic battle to keep the blaze from pushing southward through a key park and into the city proper while other teams scrambled to put out roof fires at the edge of town.

The evacuation area was expanded overnight as the eastern and western flanks advanced on the neighboring communities of Montecito and Goleta.

As of Friday morning, more than 20,000 area residents were ordered to leave their homes and nearly 17,000 others were warned to be ready to flee at a moment's notice, county officials said. That amounts to over a third of the population of Santa Barbara, located 90 miles (145 km) northwest of Los Angeles.