TORONTO>> The season’s first major wildfire continued to burn across Western Canada as firefighters tamed the fast-spreading blaze while authorities evacuated thousands of residents and warned of poor air quality from British Columbia to Ontario.

Residents in a town in British Columbia were evacuated while many in Fort McMurray, an oil hub in Alberta that faced extensive damage from wildfires in 2016, were asked to prepare to leave.

On Sunday, authorities said the fire had subdued but was expected to increase as the temperatures soar.

Alberta said the wildfire was extreme and out of control, located 16 km (9.94 miles) southwest of Fort McMurray. It grew significantly over the weekend and was 5,500 hectares (13,590.8 acres) in size, growing several folds than what was reported earlier.

In British Columbia, thousands of residents in Northern Rockies Regional Municipality and Fort Nelson First Nations were asked to evacuate as the blaze spread in size to 2,483 hectares.

Northern Rockies Regional Municipality Mayor Rob Fraser in a television interview said most of the 3,500 residents in and around Fort Nelson had been evacuated.

Fraser said the fire was started by a tree blown down by strong winds falling onto a power line.

Six crews of wildland firefighters, 13 helicopters and airtankers will tame the fire on Sunday, said Alberta authorities.

Evacuation alerts were in place for Fort McMurray, Saprae Creek Estates and expanded to Gregoire Lake Estates and Rickards Landing Industrial Park late Saturday.

Although there is no immediate risk to these communities, the alert ensures residents are prepared to evacuate if conditions change.

Smoke in Fort McMurray on Saturday was coming from fires in northern British Columbia, Alberta said.

Environment Canada issued a special air quality statement that extends from British Columbia to Ontario on Sunday.

The federal government has warned Canada faces another “catastrophic” wildfire season as it forecast higher-than-normal spring and summer temperatures across much of the country, boosted by El Nino weather conditions.

Canada experienced one of its warmest winters with low to non-existent snow in many areas, raising fears ahead of a hot summer triggering blazes in forests and wildlands amid an ongoing drought.

In 2016, more than 80,000 people evacuated from Fort McMurray as a fire torched thousands of homes and buildings.