Calming wind early Saturday helped firefighters battle a 3,700-acre wildfire that prompted a voluntary evacuation of about 200 ridge-top homes.

Fierce Santa Ana wind fanned the late-season blaze that started early Friday in School Canyon — a hilly, rocky area between Ventura and Ojai, about 60 miles northwest of Los Angeles.

The blaze was 30 percent contained early Saturday. After mapping, fire officials reduced the size of the blaze from 4,000 to 3,700 acres.

"We still have a few hot spots, but the fire is mostly lying down," Inspector Ron Haralson of the Los Angeles County Fire Department said.

The origin point and cause of the fire were under investigation.

At midmorning Friday, a wall of flames as high as 30 feet snaked along hillsides, and by early afternoon a huge plume of whiskey-brown smoke carried ash to the nearby Pacific Ocean.

In just a few hours, the wind-driven fire tripled in size. But the fire calmed down in the early evening as a cooler onshore breeze helped lower the wind and the temperature.

The National Weather Service canceled a wind advisory, but forecasters cautioned the wind would continue in the area through early Sunday at 15 to 25 mph with isolated gusts near 35 mph.

The fire roared down School Canyon heading to the northern edge of Ventura. At one point, it burned to the backyards of several large homes.

"We have a lot of crews up there and are making every effort to protect those structures," said Joe Luna, a spokesman with the Ventura County Fire Department. "But we are confident that the winds — when they calm down — will allow us to put this out."

Many of the stucco homes in the area have tile roofs, and fire officials said requirements that brush be cleared around houses had helped.

Still, firefighting equipment was headed to Ventura from throughout the state. Bulldozers and hotshot crews worked their way up Highway 101 from Los Angeles. Water-dropping helicopters and fixed-wing aircraft also were called in to assist firefighters on the ground.

Late Friday, FEMA authorized the use of federal funds to help the state battle the fire.