Firefighters battling a wind-stoked blaze that has forced evacuations gained ground even as the blaze burned through bone-dry rugged hills in two Northern California counties.

About 2,000 firefighters took a stand against the flames Wednesday, some of them lighting backfires along a road as plumes of black and white smoke rose into the sky.

Most had been reassigned from a massive fire nearby that charred 109 square miles, but was 95 percent contained after destroying 43 homes.

"We made great progress and that allowed us to move those resources and personnel" said Daniel Berlant, a spokesman for California Department of Forestry and Fire Protection.

Berlant said a portion of the new fire's northern edge merged with the massive blaze.

The new fire in Lake and Napa counties had expanded across 32 square miles. The fire was just 16 percent contained by Wednesday night, fire officials said. Full containment wasn't expected until Monday.

The blaze was threatening 50 structures, but no homes have been destroyed. No injuries have been reported.

At least 150 people have evacuated their homes since Sunday. Some in the region about 100 miles north of San Francisco had only recently returned after fleeing an earlier blaze.

The fire began in dry timber and brush Sunday several miles from the community of Lower Lake. It leapt from Lake County into Napa County, but no vineyards were threatened in the famous wine-growing region.

Empire Mini Storage manager Desiree Mcalear said the business in Middletown has had numerous calls and visits from people who want to rent units in case they have to evacuate.

"They're absolutely scared and terrified," she said. "If the winds decide to blow this way, then we all need to take action. Right now, we have the luxury of waiting and being patient."

The causes of the fires remain under investigation.

Temperatures have been relatively mild, but the gusty winds and dry conditions have stoked the flames.

In Southern California, evacuation orders were lifted as crews continued to surround a small wildfire sparked by a burning motor home in rural Riverside County.

One person from the motor home was burned, officials said. Three firefighters were taken to hospitals with minor injuries.

The blaze about halfway between Temecula and Palm Desert had been held to 450 acres and was 70 percent contained, with full containment expected Friday, state fire officials said.

Statewide, 16 active wildfires were burning and being fought by more than 11,000 firefighters.