A massive wildfire could double in size by the end of Saturday, Canadian officials fear, as they continue to evacuate residents of fire-ravaged Fort McMurray from work camps north of Alberta's oil sands city.
Thousands more displaced residents were getting a sobering drive-by view of their burned-out city as convoys continued.
Police and military are overseeing another procession of vehicles, and the mass airlift of evacuees was also set to resume.
About 2,500 vehicles and 7,000 people had passed through Fort McMurray on Friday despite a one-hour interruption due to heavy smoke, authorities said.
A day after 8,000 people were flown out, authorities said 5,500 more were expected to have been evacuated by the end of Friday and another 4,000 on Saturday.
More than 80,000 people have left Fort McMurray in the heart of Canada' oil sands, where the fire has torched 1,600 homes and other buildings. The mass evacuation forced as much as a quarter of Canada's oil output offline and is expected to have an impact on a country already hurt by a dramatic fall in the price of oil.
The Alberta provincial government, which declared a state of emergency, said Friday the size of the blaze had grown to about 1,000 square kilometres (390 square miles). No deaths or injuries were reported.
"The city of Fort McMurray is not safe to return to, and this will be true for a significant period of time," Alberta premier Rachel Notley said.
Chad Morrison, Alberta's manager of wildfire prevention, said there was a "high potential that the fire could double in size" by the end of Saturday.
He expected the fire to expand into a more remote forested area north east and away from Fort McMurray. Extremely dry conditions and a temperature of 27C (81F) was expected on Saturday along with strong winds, he said.
"We have not seen rain in this area for the last two months of significance," Morrison said. "This fire will continue to burn for a very long time until we see some significant rain."
Environment Canada forecast a 40% chance of showers in the area on Sunday. Morrison said cooler weather was expected Sunday and Monday.
Jim Dunstan was in the convoy that passed through Fort McMurray, with his wife, Tracy, and two young sons. "It was shocking to see the damaged cars all burned on the side of the road. It made you feel lucky to get out of there," he said.
In Edmonton, between 4,500 and 5,000 evacuees arrived at the airport on at least 45 flights Friday, said airport spokesman Chris Chodan. In total, more than 300 flights have arrived with evacuees since Tuesday, he said.
About 25,000 evacuees moved north in the hours after Tuesday's mandatory evacuation, where oil sands work camps that usually house employees were used to house evacuees. Officials are moving everyone south where it is safer.
All intersections along the convoy route have been blocked off and evacuees are not being allowed back to check on their homes in Fort McMurray. The city is surrounded by wilderness, and there are essentially only two ways out via road.
Fanned by high winds, scorching heat and low humidity, the fire grew from 75 square kilometres (29 square miles) Tuesday to 100 square kilometres (39 square miles) on Wednesday, but by Thursday it was almost nine times that - at 850 square kilometres (330 square miles).
The fire was so large that smoke is blanketing parts of the neighbouring province of Saskatchewan where Environment Canada has issued special air quality statements for several areas.
The region has the third-largest reserves of oil in the world behind Saudi Arabia and Venezuela.