Canadian officials ordered the evacuation of the Northwest Territories’ capital of Yellowknife and several smaller communities as a massive wildfire threatened the town of Hay River overnight.

Teams were working to evacuate Hay River, a community of some 3,000 on Great Slave Lake, by bus or plane on Wednesday night as the fire approached.

“Hay River saw the fire south of their community increase, get closer to the city today,” fire information officer Mike Westwick said at a news briefing on Wednesday evening. “We saw highly active fire in that area and it was moving quickly.”

Westwick said the blaze could reach Yellowknife by this weekend barring rain and that residents of the capital were also being asked to leave as part of a “phased evacuation” beginning with the most threatened communities.

So far no deaths have been reported from the Yellowknife fire but several structures have been destroyed. Yellowknife has a population of around 20,000 people and lies 250 miles (400 km) south of the Arctic circle.

Canada is enduring its worst wildfire season with more than 1,000 active fires burning across the country, including 230 in the Northwest Territories.

Thousands of residents of the sparsely populated territory have already fled smaller communities and the hamlet of Enterprise near the Alberta border was almost entirely destroyed by a blaze that swept through on Sunday.

Northwest Territories Premier Caroline Cochrane said some Yellowknife residents were preemptively leaving the city but urged people to remain calm and warned that highways could close suddenly because of the fire risk.

“I’ve never seen so many vehicles leaving town,” Cochrane said. “There’s all kinds of rumors out there, but be ready and evacuate if necessary. Be calm. Do not panic.”

NWT Fire said the 163,000 hectare (402,781 acres) wildfire is currently 17 km from Yellowknife and would likely reach Highway 3, the only highway connecting the city to the rest of Canada, on Thursday.

“There is risk to the City of Yellowknife. Our team, alongside the City of Yellowknife, are doing everything possible to slow the growth of this fire and protect the community,” NWT Fire said.

The Northwest Territories declared a state of emergency late Tuesday and the Canadian military has been mobilized to help tackle the blazes and airlift some residents to safety.

Cochrane spoke to Canadian Prime Minister Justin Trudeau about the wildfire situation on Wednesday afternoon. Trudeau reaffirmed the federal government’s ongoing commitment to help the territory, according to a readout of their conversation.

Western Canada is enduring a heat wave that saw 19 daily heat records broken on Tuesday and is fuelling hundreds of out-of-control wildfires.

In the Pacific province of British Columbia around 80 people were forced to shelter in place in a mountain guesthouse after their only way out was cut off by a rapidly expanding blaze.

The stranded people, including lodge guests and campers from nearby campgrounds, sheltered overnight at the Cathedral Lakes Lodge near Keremeos in the south of the province before being brought down the mountain in vehicles on Wednesday afternoon.

Blazes have engulfed parts of nearly all 13 Canadian provinces and territories this year, forcing home evacuations, disrupting oil and gas production and drawing in federal as well as international firefighting resources.