An aerial view of the fire on Saturday. (B.C. Wildfire Management Branch)

The number of residents forced out of their homes because of wildfires in the tinder-dry Okanagan region of B.C. continues to climb.

The latest reports indicate as many as 11,000 residents in the area have been placed under an evacuation order and asked to leave their homes, while an additional 6,000 are under an evacuation alert.

Since the fires started Saturday afternoon, flames have destroyed at least nine buildings, including three houses, and charred 3.5 square kilometres in West Kelowna.

Firefighters were being hampered by gusty winds, dry conditions and high temperatures. Forecasters said the daily high in the Kelowna area would be at least 30 C until next weekend.

There were more than 150 people battling the blaze, including 100 firefighters trained to fight fires in homes and other structures, as well as 17 pieces of heavy equipment, up to 10 helicopters and eight air tankers.

"It's something that we feared would happen and it has happened," said Coun. Brian Winsby, among those who stayed away from home overnight. "Hopefully, it won't be as serious as a lot of people have feared."

Officials say they have not determined what caused the fire.

Local mill escapes major damage

Thousands of people were driven from their homes as the wildfire continued to grow Sunday. (Sumbitted by Anna Mason)

About 4,500 homes in the Glenrosa neighbourhood had to be evacuated because of the largest of three fires.

A local mill, Gorman Bros. Lumber Ltd., which employs more than 300 people in the region, was saved from major fire damage.

A crew of about 20 of the mill's employees worked through Saturday night hosing down the perimeter.

"It's very spectacular, to have that black all around you and then the mill itself is still standing," said employee Mark Blazina.

"We had a number of fires on the roofs of different buildings. We did have one structure damaged … and that was in the roof, and we managed to get that out quick enough that it didn't cause any major damage."

Two family properties owned by the Gorman brothers on the sawmill site were overtaken by the fire Saturday evening.

Blazina said a big fire continued to loom behind the mill Sunday and the threat of sparks is cause for concern.

3 more fires burning

A second fire continued to burn Sunday four kilometres from the Glenrosa blaze in the Rose Valley Reservoir. That blaze is estimated to be one square kilometre in size.

Officials released an evacuation alert Sunday afternoon warning residents at 50 addresses on Bear Creek Road, Dougmac Road, Petterson Road and Rose Valley Road to be prepared to leave on very short notice. An additional 1,500 homes were put on evacuation alert Sunday morning.

Air tankers and firefighters worked to contain the blaze throughout the day Sunday. (CBC)

The fire has not been contained, but crews have laid lines of fire retardant around 90 per cent of the fire.

More than 125 firefighters, 10 helicopters and several pieces of heavy machinery were sent out to battle the blaze.

Officials say they believe that fire was caused by a person, but the details are still under investigation.

A third fire, burning on Terrace Mountain near Fintry, north of Kelowna, grew to cover 2.5 square kilometres on Sunday. About 60 firefighters and four helicopters were working to try to get it under control.

Officials they believe the fire was caused by a person.

The largest fire jumped Highway 97 leading into West Kelowna after the road had been closed in both directions, and the blaze began moving east toward Okanagan Lake.

Thick smoke forced the closure of Highway 97 where it connects to Highway 97C.

"[The smoke] is terrible, absolutely terrible," said Derek Burgess, who is helping to find shelter for people who show up at the Mount Boucherie Complex.

Embers and ash from the Glenrosa fire have been falling on his deck in downtown Kelowna, eight kilometres away, he said.

Emergency evacuation centres up and running

Community centres and schools were opened for those who needed a place to stay, and every hotel room as far as Penticton was booked.

Residents affected by the evacuation order are being asked to report to emergency evacuation reception centres at Royal LePage Place at 2760 Cameron Rd. and Mount Boucherie Secondary School at 2751 Cameron Rd.

Concerned residents or relatives can call 1-250-469-8490. Residents who are unable to reach evacuation centres are asked to call 778-797-2269.

After being briefed on the damage, Forests Minister Pat Bell said the Glenrosa fire had the potential to be worse than the firestorm that devastated the city in 2003.

"I don't think you can compare it to 2003 at all. In 2003, you were in a very rural area, the homes were spread out. In the Glenrosa subdivision, much of it is much like any subdivision in British Columbia with smaller lots that are closer together," Bell said.