100 MILE HOUSE, B.C. -- A fast-moving wildfire has forced as many as 3,600 people to leave their homes in central British Columbia as another community was added to an evacuation order Friday.

Al Richmond, chairman of the Cariboo Regional District, said people have been ordered to leave their homes about 200 kilometres northwest of Kamloops.

The evacuation order applied to about 2,100 properties around 105 Mile House, 108 Mile House and the west shore of Lac La Hache, while about 600 properties were under evacuation alert, he said.

No properties were at risk of burning by Friday afternoon, but officials issued the order to leave because of concerns about changing wind patterns and heavy smoke cutting off access roads and evacuation routes, Richmond said.

"When the winds shift, as they are predicted to do, the threat becomes greater, smoke would move into communities, making it difficult to get people out," he said, describing the 12-square-kilometre blaze as volatile. "Moving now will eliminate that element of panic."

There are only two exits along about 50 kilometres of road in the 108 Mile House area where 2,500 people have been ordered to leave, Skrepnek said.

"It's prudent to get them out now."

Two reception centres for evacuees have been set up, at a curling rink in 100 Mile House and a hotel in Williams Lake.

Kevin Skrepnek, chief information officer for the BC Wildfire Service, said the fire broke out Thursday and that 120 firefighters have been assigned to build guards along the fire's eastern flank, nearest to the communities ordered to evacuate.

Skrepnek said Friday that the cause of the blaze remains under investigation and that more equipment was en route, though heavy smoke and poor visibility could hamper the use of air tankers.

Thirty-three homes in the direct path of the fire were ordered to evacuate shortly after the fire started. Richmond said fire crews installed sprinkler systems to protect the homes.

"The fire has burned past them and those structures are still in place, so those units ... protected those homes for those folks," he said.

Another fire that started Thursday near Ashcroft, about 100 kilometres west of Kamloops, also triggered an evacuation order, although no details were released by officials on the number of people affected.

The BC Wildfire Service says buildings were affected by the blaze, which was about 50 hectares in size.

The fire forced Highway 1 to be closed in both directions between Ashcroft and Cache Creek, while Highway 97C running through Ashcroft was also closed, said Drive BC.