The out-of-control blaze has consumed entire neighborhoods of Fort McMurray in Canada's energy heartland and officials warn its spread now threatens two oil sands sites south of the city, Reuters wrote.
The wildfire has already forced precautionary production cuts or shutdowns at about a dozen major facilities, eating into a global crude surplus and supporting oil prices this week.
"The damage to the community of Fort McMurray is extensive and the city is not safe for residents," said Alberta Premier Rachel Notley in a press briefing late Thursday, as those stranded in camps and on the roadside to the north of the city clamored for answers.
"It is simply not possible, nor is it responsible to speculate on a time when citizens will be able to return. We do know that it will not be a matter of days," she said.
Read alsoFort McMurray fire: State of emergency declaredThree days after the residents were ordered to leave Fort McMurray, firefighters were still battling to protect homes, businesses and other structures from the flames. More than 1,600 structures, including hundreds of homes, had been destroyed by Wednesday morning. Officials declined on Thursday to estimate how many more had been lost.
The communities of Anzac and Gregoire Lake Estates about 50 kilometers (31 miles) south of Fort McMurray were "under extreme threat," late Thursday, as the flames spread to the southeast.
CNOOC Nexen's Long Lake oil sands facility and Athabasca Oil's Hangingstone project are also in danger as winds blow southward, according to emergency officials.
There have been no known casualties from the blaze itself, but fatalities were reported in a car crash along the evacuation route.
Although the cause of the fire was unknown, officials said tinder-dry brush, low humidity, and hot, gusting winds left crews unable to stop the massive conflagration.
The blaze, which erupted on Sunday, grew more than tenfold from 18,500 acres (7,500 hectares) on Wednesday to some 210,000 acres (85,000 hectares) on Thursday, an area roughly 10 times the size of Manhattan.
The dry weather conditions prompted the province to issue a fire ban for parks and protected areas on Thursday.
