An aerial view shows smoke rising from raging wildfires in Fort McMurray, Alberta, Canada, on May 4, 2016.

Wildfires in the Canadian province of Alberta this week have engulfed thousands of homes, forced the evacuation of an entire city, and spewed smoke and ash into the air.

Fire conditions remained “extreme” on Thursday, Alberta’s government said in a statement. A total 49 wildfires are burning, with seven considered “out of control.” Twenty-three of the fires have been contained. Eighteen new blazes have started since Wednesday.

A small blaze began in Fort McMurray, located in Canada’s oil-sands country, over the weekend. Dry conditions and a sudden spike in temperature to 32 degrees Celsius, or about 90 degrees Fahrenheit, fed the flames, which by Tuesday had become too severe to control. The Regional Municipality of Wood Buffalo, where Fort McMurray is located, ordered a mandatory evacuation of the city Tuesday night. About 88,000 people have evacuated Fort McMurray since.

The exodus clogged the only major highway that connects Fort McMurray to the rest of the province. Thousands of people flocked to Highway 63, fleeing as Alberta’s boreal forests burned next to them, before the highway was closed:

Two people were killed in a two-vehicle collision Wednesday on neighboring Highway 881 as they evacuated the city, CBC reported.