Canada's western province of British Columbia declared a state of emergency on Friday as firefighters battled a wildfire raging in the hills and mountains above the town of West Kelowna forcing thousands of evacuations.

West Kelowna, a city of 36,000 people is some 300 kilometres east of Vancouver. Wildfires and evacuations were also being carried out in Kelowna, a city with a population of about 150,000 also on Okanagan Lake.

The flames and smoke were visible from West Kelowna, according to a Reuters witness, and smoke filled the valley surrounding the lake.

Officials said the next 24 to 48 hours could be the most difficult. Earlier the airspace in the area was closed to clear the way for water bombers.

"Over the past 24 hours, the situation has evolved rapidly and we are in for an extremely challenging situation in the days ahead," the government of British Columbia said in a statement.

"We fought hard last night to protect our community," Jason Brolund, West Kelowna fire chief, told reporters. "Night turned to day because of the orange glow of the clouds and the fire."

More than 2,400 properties were evacuated, officials said, and thousands more are on alert to leave with little notice if necessary. Several structures were destroyed in West Kelowna during the night, he said. (Reuters)