At least half of a northern Alberta city was ordered evacuated Tuesday as a wildfire whipped by winds engulfed homes and sent ash raining down on residents.

A local radio reporter said a trailer park that had been evacuated on Monday was on fire and flames were advancing toward businesses.

"It's chaos on the roads. People are panicking. It's gridlock on the roads. Flames are right next to a gas station," said Carina Van Heerde with radio station KAOS.

The main road into Fort McMurray, was closed at the southern entrance to the city after flames jumped the road.

Pictures posted on Twitter showed long lines of traffic and skies darkened by thick smoke as flames licked the edges of roads.

Fort McMurray is the capital of Alberta's oil sands region and had a population of 61,000, according to the 2011 census.

Crews had seemed to be making progress controlling the blaze, burning since the weekend, but the situation worsened quickly on Tuesday. By mid-afternoon people from three neighborhoods were told to leave immediately.

Unseasonably hot temperatures combined with dry conditions have transformed the boreal forest in much of Alberta into a tinder box. The wildfire threat ranging from very high to extreme.

The Alberta government banned all open fires except in designated camping sites in forested areas due to the threat. There were about 30 fires burning in the province.

The province was calling in more reinforcements to Fort McMurray, including 100 more firefighters and a giant helicopter that can dump more than 2,000 liters (500 gallons) of water at a time.