The only land convoy evacuating the Canadian city of Fort McMurray has been disrupted due to 200ft (60m) flames flanking the road, officials say.
Parts of the city in the province of Alberta have been destroyed after a huge wildfire struck earlier this week.
Officials say the fire will double in size in the coming 24 hours.
Residents have been told they must evacuate and some have left by air, with 5,500 flying out on Friday and another 4,000 due to do so on Saturday.
Tens of thousands of people have already left Fort McMurray with more than 300 evacuation flights to the provincial capital Edmonton since Tuesday.
The police-escorted road convoy of 1,500 vehicles was due to pass by the southern part of the city but was stopped for an hour on Friday afternoon.
“We stopped due to heavy smoke,” said Sgt Jack Poitras of the Royal Canadian Mounted Police. “You get flames of 100, 200ft up in the air on both sides of the road so it’s not safe.”
The provincial government in Alberta has declared a state of emergency and will provide C$100 million ($77 million) in cash to evacuees.
Alberta Premier Rachel Notley said the “extensive” damage would take “many months” to repair.
She said: “The downtown is largely intact. The hospital is still standing. The telephone centre is intact. The water treatment centre is back up and running. Municipal buildings and the aeroplane remain intact.”
The city is in the heart of Canada’s oil country and as much as a quarter of the country’s oil production has been halted by the fire.
Two oil sand sites are directly threatened by the blaze while 10 operators have cut production.
The fire now covers an area larger than New York City.