"We know the fire is bigger than that, but it's in some difficult terrain so it's hard to know," said fire spokesman Bill Nash.
A cluster of RVs in a parking lot was destroyed as flames moved close to a mobile home park.
About 2,000 homes were threatened by flames and 15 sustained damage, but none was destroyed, officials said.
No firefighter injuries were reported.
Fire officials said Thursday afternoon that a hazardous materials team will deal with a store of highly toxic pesticides that caught fire at a Laguna Farms property, according the Ventura County Star. Area residents were warned to stay out of the smoke as much as possible.
Evacuations orders were lifted in some neighborhoods Thursday evening, including the smoke-choked campus of California State University, Channel Islands, which has about 5,000 students. But the danger was far from over.
"The weather is mitigating a little bit, so we're taking every opportunity to improve our lines, but we're not off the hook," Nash said. "Tomorrow we expect the Santa Ana winds to quiet down, but it's still expected to be quite warm."
A more complete damage assessment will be done Friday, Nash said.
More than 925 firefighters and law enforcement officials from multiple agencies worked to protect homes around Camarillo Springs Golf Course and in a section of adjacent Thousand Oaks.
Air tankers were grounded for a time in the afternoon because of the winds, which gusted to 50 mph. Planes and helicopters dropped water and retardant until sunset.
The Santa Ana winds sent plumes of smoke and embers over the homes and strawberry fields to the south. At midday, farm sheds burst into flames in a clearing amid rows of crops.
The vegetation-withering dry winds out of the northeast caused humidity levels to plunge from 80 percent to single digits in less than an hour. Temperatures soared into the 90s in Camarillo.
The area is at the western edge of the Santa Monica Mountains, which abruptly descend to a coastal agricultural plain. It was possible the flames could burn all the way to the Pacific Ocean, about 10 miles from the start point.
For a while, the California Highway Patrol closed a 10-mile stretch of Pacific Coast Highway at Point Mugu. It was reopened at midafternoon around the time coastal weather stations recorded a localized return of moisture-bearing winds off the ocean, although hot Santa Anas kept blowing a few miles inland.
Mark Brewer, 52, was resting at an evacuation center Thursday afternoon after he and about 25 adults and children were evacuated from a county-run homeless shelter. Brewer could see flames coming down a hillside toward the building before he left.
"This is a part of being in Southern California, just like earthquakes," Brewer said.
Brewer, who lost his job in the mortgage industry a year and a half ago, managed to grab his laptop, some clothes and papers from the room he lives in before traveling to a Camarillo church, where evacuees were glued to televisions watching fire coverage.
About 100 miles to the east, two homes, a number of outbuildings and several vehicles were destroyed, and two other homes were damaged in a 5-acre grass fire that prompted the evacuation of an elementary school in Jurupa Valley, said Theresa Williams, a spokeswoman for CalFire.
The blazes could signal a difficult fire season ahead.
Officials with the National Interagency Fire Center in Boise said Wednesday in their first 2013 summer outlook that a dry winter and expected warming trend mean the potential for significant fire activity will be above normal on the West Coast, in the Southwest and portions of Idaho and Montana.
Meanwhile, the California Department of Water Resources found the water content in the snowpack was just 17 percent of normal. The snowmelt is a vital water source for the state.
Elsewhere in California, crews made progress on a 4 1/2-square-mile fire burning in the foothills of the San Bernardino Mountains north of Banning, Riverside County fire spokeswoman Jody Hagemann said.
The fire, which burned a home Wednesday, was 40 percent contained with only sporadic flames showing.
In Northern California, a fire in a remote area of brush and timber north of the town of Butte Meadows grew to more than 3 square miles, with 10 percent containment, state fire spokesman Daniel Berlant said. Several fires smaller than 200 acres burned in Sonoma, Glenn and Butte counties.