Fire crews continued to attack a major wildfire in the central B.C. Interior on Sunday, and while officials reported some progress, all evacuation orders and alerts remained in effect in the Cariboo region.

The Mount McLean fire near the town of Lillooet remained at 50 per cent contained, the B.C. Forest Service reported.

Firefighters were mopping up along the east perimeter of the blaze, with helicopters dousing hot spots. Crews were set to rappel down steep slopes on the west flank and build helipads to allow access for ground crews to attack the fire directly, the service said in a release.

Ten pieces of heavy equipment, 67 firefighters, 80 support personnel and 11 helicopters were deployed Sunday, while 12 structural protection units were maintained at Seton Portage, west of Lillooet.

In the Okanagan, an estimated 2,150 people remained on evacuation order and 2,500 residents were on evacuation alert and had to be prepared to leave their homes on short notice as firefighters continued to battle the Terrace Mountain fire.

Area residents will clearly see large columns of smoke as crews attack the north flank of the fire with a controlled burn, the forest service said.

Elsewhere, the fire risk to populated areas of the Bella Coola Valley diminished, but the closures affecting Highway 20 at Heckman Pass continued to cause challenges for travellers and supply vehicles, officials said. Any potential highway openings are subject to fire behaviour and may be cancelled at any time.

The situation is expected to improve Monday, when rain is expected in the area.

In the central Interior, the Kamloops Fire Centre has prohibited the use of portable propane campfires. A ban on open fires remains in effect.