An out-of-control wildfire has destroyed much of one neighbourhood in the remote Canadian city of Fort McMurray and badly damaged other areas, the local government said.
It came hours after it ordered all 80,000 residents to leave in the biggest evacuation in the area's history.
Firefighters in the northeastern Alberta city at the heart of Canada's oil sands were bracing for another tough day.
Hot, dry weather has made it difficult to being the fire under control. A forecast for potential fire intensity showed much of the area around at class 6, the highest possible level.
Some 44,000 people had fled the city by late on Tuesday, but evacuations were delayed by petrol shortages, local officials said.
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No injuries or deaths were reported.
In a bulletin posted on Twitter in the early morning, the regional government said 80 per cent of Beacon Hill, a residential area at the south end of town, had been lost.
Two other neighbourhoods, Abasand and Waterways, were listed as "serious loss".
By early Wednesday morning Shell had closed one oil sands mine and was in the process of closing another.
Chief Financial Officer Simon Henry said the company's priority was safety, and to support the community. Henry said upgraders, which process oil sands to produce crude, would operate for a few more days.
Alberta Health Services said in a statement that all patients had been successfully evacuated from Fort McMurray's hospital.
