Hopes of a speedy return have been dashed in Fort McMurray as wildfires burning with new-found vigour are raging around the city, upending plans to restart oil production and restore the local services needed for residents to re-enter the community.

Nearly a week of cool weather had provided the firefighters around Fort McMurray with a respite to beat back the once-raging inferno and rebuild fire defences. That lull came to an end on Monday, as strong winds and baking heat drove a wall of flames toward the sprawling oil sands facilities north of the city.

"We anticipated a very active fire day, and as you've all since heard, that's exactly what we got," Alberta Premier Rachel Notley said on Tuesday morning in Edmonton. "Mother nature continues to be our foe."

Story continues below advertisement

Nearly 8,000 people were evacuated from work camps north of Fort McMurray late Monday as the flames closed in on oil sands facilities operated by Suncor and Syncrude. Of those, 2,000 heeded the government's advice and drove south, while the other 6,000 headed north.

This was a second evacuation for many workers who had fled two weeks ago, only to be sent back to resume oil production. The oil and gas companies will need to pay for this second evacuation, said Scott Long, executive director of the Alberta Emergency Management Agency.

Complicating matters, a home exploded inside of Fort McMurray on Monday night in an area where natural gas service was being restored. Officials couldn't immediately link the gas to the explosion. With 60 per cent of the city's gas mains now reactivated, the process has been put on hold pending an investigation.

Ten homes were destroyed by the explosion and another fire in the community, the Premier said – proof, she added, that the government should remain cautious and not allow residents to return before it is completely safe.

More than 1,950 firefighters are now deployed battling fires across Alberta. Two weeks after more than 80,000 residents were forced to flee Fort McMurray, the fire around Canada's oil sands capital now covers 3,550 square kilometres – nearly six times the size of Toronto.

"We don't see any relief at this point until we see rain in the forecast," provincial wildfire manager Chad Morrison said Tuesday. There hasn't been significant rain in Fort McMurray for two months.

Plans to clean the city's health centre and restock grocery stores have been scuttled because of the fire risk and extremely poor air quality in the city. On Monday morning, the air-quality health index in Fort McMurray was measured at 38 on a scale that ranges from one to 10. It fell to 13 on Tuesday.

Story continues below advertisement

The smoke is also reducing visibility and hampering flights by the 47 helicopters and 29 air tankers dropping water on the flames because aircraft must stay grounded until the wind co-operates and clears the sky.

"We got [kicked hard] yesterday and it is going to happen again today," Paul Spring, the owner of Phoenix Heli-Flight, said Tuesday morning.

The air quality in the city is horrible, Mr. Spring said. "You'd wake up around four in the morning because you could barely breathe. You just felt like your building is on fire [because] it is so smoky."

The veteran firefighter now fears that the battle around the city could last through the summer.

The fire on Tuesday chewed up the Blacksand Executive Lodge, a work camp with 665 rooms that was put under a mandatory evacuation Monday evening. The re-energized fire also threatened a nearby Noralta Lodge complex on Tuesday. "It's at the doorstep," Mr. Morrison said.

Clean Harbors' Ruth Lake Lodge is about five to eight kilometres north of the inferno, according to Kirk Duffee, the firm's president of oil and gas field services. "It is enough to make us worry," he said in an interview Tuesday. "We're on very, very high alert."

Story continues below advertisement

While there are natural and industrial fire breaks between the blaze and the 600-room facility, the company is readying its firefighting plans. Mr. Duffee said it hopes to have fire cannons ready within the next 48 hours.

With fires burning at the gates of some of Canada's most important industrial facilities, some of the nearly 6,000 workers trapped north of Fort McMurray on Tuesday were loaded onto buses and transported to an airstrip operated by Suncor so they could be flown south.

A team leader who works at Suncor's base plant was among those who delivered the message to other employees Tuesday afternoon. "Everybody is starting to pack," he said.

Stanley Caines, an evacuee from Fort McMurray's northern suburbs, said he worries the government and oil industry may have moved too hastily to get the city and its main industry back up and running.

"I would like to see them take their time‎," Mr. Caines said at an evacuee centre in Lac La Biche, Alta. He has yet to learn if his house escaped the blaze.