Thousands of people are being evacuated from the city of Yellowknife in Canada’s Northwest Territories as bushfires continue to rage. It’s part of a wider bushfire crisis that has affected tens of thousands of people and large swathes of land across Canada this summer.

There are currently more than 1,000 ongoing bushfires, including about 230 in the Northwest Territories. More than 20,000 Yellowknife residents had until Friday to leave by road or on emergency flights. The flames are moving closer to the edges of the road, reducing visibility due to thick smoke.

Flights to the neighboring province of Alberta are to depart from Yellowknife. The evacuation came as a wildfire was 16 kilometers (10 miles) from town. The situation forced Yellowknife to declare an emergency and displaced half the population of the Northwest Territories.

Canadian military forces participated in the evacuation efforts, with aircraft and soldiers deployed to help fight the fires. The Prime Minister of Canada, Justin Trudeau, has pledged his support in every way possible. The Yellowknife evacuation is the largest in the territory’s history, with many residents having to leave their homes for the second time in recent months.

This season’s wildfires have been particularly intense, burning more than 13.5 million hectares (33.4 million acres) of land across Canada. This crisis has resulted in the death of four people so far. In 2016, the city of Fort McMurray in Alberta was also evacuated due to wildfires, which destroyed more than 2,000 homes and businesses.