The unpredictable wildfire burning near Fort McMurray has forced rebuilding crews out of the ravaged city and caused more than 8,000 oil workers to flee camps to the north.

The fire has grown dramatically since Monday and is now estimated to cover 3,500 square kilometres -- nearly five times the size of New York City.

A thick, hazy mass of smoke has blanketed the region, painting the sky orange and creating dangerous air quality. On a one-to-ten scale, air conditions were measured at 13 on Tuesday – a level deemed a “very high risk” by Alberta’s Air Quality Health Index.

About 400 people working to clean up a Fort McMurray hospital have been pulled from the city, adding further setbacks to restoration plans. A company working on the city’s natural gas system has also paused its efforts.

Alberta Premier Rachel Notley said the setbacks have forced officials to revisit their timeline to get Fort McMurray residents back home. Speaking at an Edmonton press conference on Tuesday, Notley said she hopes to have more specific re-entry plans “within the week.”

"Safety will be and must be our first and principle priority," she said.

Oil workers across the region were forced to flee Monday night as flames edged closer to the sites. The Blacksand Lodge, which housed about 660 workers, burned to the ground shortly after workers left.

Provincial wildfire officials said the flames also threatened oilsands facilities and camps north of Fort McMurray, including the Suncor and Syncrude sites.

In Fort McMurray itself, two separate explosions destroyed a total of 10 buildings, firefighting officials confirmed at a news conference on Tuesday.

The explosions occurred on Monday night at separate sites in the Dickinsfield and Thickwood neighbourhoods, Notley said.

"These fires were swiftly controlled and put out promptly," Notley said.

The Regional Municipality of Wood Buffalo said in a separate statement that the areas where the explosions occurred are "no longer under immediate threat."

Dry and windy conditions have caused the fire to spread quickly, according to wildfire information officer Travis Fairweather.

“It’s a very large increase in size in a single day,” Fairweather told CTV News Channel on Tuesday afternoon.

And while the forecast calls for a chance of rain for Thursday or Friday, officials say the blaze remains largely unpredictable until a large amount of rain falls.

“It can pick up and start spreading very quickly,” Fairweather said.

Notley: Fort McMurray 'mostly intact'

The premier said electricity has been restored to most undamaged parts of Fort McMurray, and to the communities of Anzac and Fort McMurray First Nation. Gas service has also been restored to 60 per cent of the city.

Fire officials said the incidents are under investigation, but it's unclear at this point whether gas services played a role in the explosions.

Notley said there are currently no active fires burning within the city limits, but "hot spots" remain.

"The community is mostly intact, notwithstanding significant losses in some parts of the city," she said.

Nineteen fires are currently burning in the province, with five of them burning out of control, Notley said.

"Mother Nature continues to be our foe,” she said.

Oil facilities at risk

Alberta wildfire manager Chad Morrison said the flames are currently threatening oilsands facilities and camps north of Fort McMurray, including the Suncor and Syncrude sites. Approximately 8,000 workers have been evacuated from camps north of the facility, and industrial firefighters are standing ready at oilsands sites to protect them from the flames.

Morrison said most of the oilsands sites are barren of vegetation, which will help keep the flames from reaching vulnerable areas.

The flames will likely reach the Saskatchewan border by the end of the day, Morrison said.

Approximately 80,000 Fort McMurray residents remain in evacuee camps south of the city, while they wait for the go-ahead order to return. The Alberta government says it has handed out $65.7 million on debit cards to evacuees, to ease their time away from home.

Fort McMurray