Crews working the Terrace Mountain fire in B.C.'s Central Okanagan had to fight fire with fire on Sunday.

"It was a pretty dramatic scene today," Mitch Miller, a fire information officer with B.C.'s Ministry of Forests and Range, told CTV News Channel on Sunday.

The goal was to bring the northern flank of the 88-square-kilometre fire down to an area known as Shorts Creek. A helicopter went in with a drip torch to set a fire in advance of the fire front -- a technique known as a burn-off.

"This one particular area was causing problems for firefighters as fire continually burned logs and logs would roll down the hill," he said.

Because it's so dry, the flames creeping down the mountain would burn the roots of trees. The trees would catch fire, topple and then slide down the mountain.

"To put firefighters down below was very dangerous, and it also posed a problem in case we had a wind event." Any flaming embers could easily jump a fire guard in that situation and open up a new front, he said.

The interior of the fire is patchy, so there's lots of material yet to burn, he said.

"So we've gone in there, we've burned it out. It's been successful, the rest of the perimeter is looking well, so good progress today," Miller said, adding the burn-off covered about 300 hectares.

Firefighters are working to build up fire guards, he said.

About 2,150 people in the area are under an evacuation order. Another 2,526 are on evacuation alert and could be asked to leave at any time.

"By bringing this fire down to Shorts Creek, we've reduced the risk that this fire could jump and continue to the north. We're not out of the woods yet ... but we're cautiously optimistic that this burnout operation was a success," Miller said.

As for those evacuated, Miller said they are worried that an approaching cold front could boost wind speeds harm fire control efforts.

"We're not going to let them move back into the area until we're confident that it's safe and they won't have to be moved again," he said.

To date, no homes have been lost to the fire, he said.

The fire, which started on July 18 and is believed to be human-caused, is currently considered 40 per cent contrained. It had been considered 90 per cent contained, causing an evacuation order to be rescinded. However, things took a turn for the worse and people had to leave again two days later.

Overall, the wildfire situation is calming down in B.C. Residents of 61 homes in the mid-coast town of Bella Coola were allowed to return home Saturday and the number of fire starts per day is down significantly from late July.

With files from The Canadian Press