A fire fighting helicopter works over wildfires that continue to threaten Fort McMurray neighborhoods in Fort McMurray, Alberta, Canada May 4, 2016. [Photo/Agencies]

TORONTO - The wildfire in western Canada has ballooned to 85,000 hectares in Fort McMurray overnight and is now billowing across a wide front south of the city, a senior official said Thursday.

The fire, which broke out early this week, has forced a massive evacuation, said Alberta Premier Rachel Notley one day after the province declared a state of emergency.

Supercharged by winds of up to 70 km/h, the Fort McMurray wildfire has grown 8 times larger Wednesday night and is expected to continue to burn out of control Thursday as more than 1,110 firefighters, 145 helicopters and 22 air tankers are fighting to protect homes and critical infrastructure across the oil sands gateway.

No firm estimates are yet available on number of structures that burned overnight but officials said Wednesday that at least 1,600 homes and buildings have been destroyed as over 88,000 residents were evacuated from Fort McMurray. Up to 90 percent of structures were burnt down in some outskirts neighborhoods.