The Rock Creek fire in B.C.'s southern Interior continues to challenge firefighters, who have yet to set up a barrier around the 37-square-kilometre blaze that's been burning since Thursday.

The fire is still very active and a thick haze is making it difficult to see and fight it, officials say.

"The reason for the smoke is due to an inversion that's going on today," said fire information officer Mike McCully. 

"We have a layer of warm, smoky air trapped under cooler air up above, which can cause us a little bit of challenges when we're working out aircraft due to reduced visibility."

Some Rock Creek residents were taken to visit the remains of their homes on Monday.

Later that day an evacuation order that was in place was downgraded to an evacuation alert — meaning residents could go home but may have to leave again on a moment's notice.

Looking for video evidence

Officials are looking for a video that apparently shows how a massive wildfire that has destroyed 30 homes in the province's southeast was sparked by a flicked cigarette, said British Columbia Forests Minister Steve Thomson.

Thomson said Monday that officials have heard about the video but have yet to see any evidence.

The 37-square-kilometre Rock Creek wildfire started Thursday and is currently burning out of control east of the southern Okanagan town of Osoyoos. Officials have already said it was human caused.

"We have no confirmation of [the video] at this time, but the investigation is ongoing and I would encourage anyone who has video to share it with the local RCMP or with our wildfire service," he said.

Besides the homes, 15 other buildings have been destroyed by the fire so far, and another 242 properties remain on evacuation order.

Rock Creek damaged vehicle

At least 30 homes and 11 properties have been damaged in the Rock Creek fire in B.C.'s southern Interior. (CBC)

Homeowners were taken into the fire-ravaged area Monday morning to assess the damage.

"It's just a drive-by to look at their homes," said Alan Stanley of the Kootenay Boundary Regional District. "They're either standing or they're not. It's pretty emotional."

The Red Cross is setting up a centre where residents can receive financial assistance, cleanup kits and other support. It is also collecting donations for families affected by B.C. wildfires this year.

About 100 personnel are working to get the Rock Creek fire under control, but hot, dry conditions are making their jobs difficult, said fire information officer Mike McCulley.

The fire is one of more than 230 blazes currently burning across B.C., said provincial fire information officer Kevin Skrepnek.

Progress on Oliver fire

He said significant progress has been made on two Oliver-area fires.

Skrepnek said the 15-square kilometre Testalinden fire burning seven kilometres south of the town is now 40 per cent contained and the three-square-kilometre Wilson Mountain wildfire burning just north of Osoyoos is about 70 per cent contained.

BC Wildfires 20150816

The wildfire in Rock Creek, B.C., has destroyed at least 30 houses and forced hundreds of people from their homes. (THE CANADIAN PRESS/Jonathan Hayward)

Evacuation orders have been lifted for residents living near both fires, though they must still be ready to leave again at a moment's notice.

Eight helicopters and five planes fighting the fires near Oliver were grounded for more than three hours Sunday due to a drone flying in the area.

Thomson was at the Oliver airport at the time and said the crews' faces showed frustration.

"Ticked off would probably be too mild a term to talk about their reaction," he said. "It's really something that is not acceptable as we have these assets in the air, supporting and protecting our communities."

Skrepnek said the province has spent $207 million fighting the nearly 1,650 wildfires across B.C. this year.

With files from Canadian Press