California wildfire expected to gain strength

SANTA BARBARA, California (CNN) -- A wildfire threatening homes in Southern California is expected to gain strength Friday, fueled by strong winds and dry conditions, officials said.

An estimated 30,000 residents of Santa Barbara County have been ordered to evacuate because of the blaze, which has scorched more than 3,500 acres and damaged or destroyed at least 75 homes, emergency officials said.

Santa Barbara County Fire Chief Tom Franklin said the fire has displayed a "roller coaster effect" because of the changing weather patterns.

"It starts off, looks kind of calm, thinking we're getting the upper hand, turns out we're not," Franklin said. "As unpredictable as the weather can be, that's about as unpredictable as the fire is going to be."

The fire has engulfed mansions in the coastal community's foothills after starting Tuesday in the Cathedral Peak area. "Nervous" in fire zone »

It was about 10 percent contained by Friday morning, fire officials said. Nearly 2,500 people are working on battling the blaze. Watch how the wind pushed fire into new neighborhoods »

"Firefighters, thank you, thank you, thank you for your hard work," California Gov. Arnold Schwarzenegger said at a Thursday briefing.

The cause of the fire is unknown, and authorities are asking anyone with information on its origin to call a tip line.

The blaze comes about six months after the Tea Fire destroyed about 200 homes in the Santa Barbara area.

"It's just horrible. We're all in a panic here. It's terrifying," iReport contributor Exton Quinn said Thursday. Are you there? Send photos, videos

Quinn said she and a friend were out shooting video Wednesday night when "all of a sudden, the wind changed and a house caught on fire just behind me."

Her duplex, on the edge of a mandatory evacuation zone, hadn't burned. But the artist and architect said she was concerned as she headed for Los Angeles on Thursday.

"I have hundreds of paintings, so I would just lose everything," she said.

CNN's Jim Kavanagh and Kara Finnstrom contributed to this report.

All About Wildfires • Santa Barbara