FORT MCMURRAY, Canada : A ferocious wildfire wreaking havoc in Canada could double in size Saturday, an official warned, cautioning the situation in the parched Alberta oil sands region was unpredictable and dangerous. “This remains a big, out of control, dangerous fire,” Public Safety Minister Ralph Goodale said of the raging inferno the size of London that forced the evacuation of the city of Fort McMurray.

Some 1,570 square kilometers (600 square miles) had been devastated since the blaze began almost a week ago and the fire had grown by an additional 50 percent in less than 24 hours, Goodale told a televised news conference.

“There is one prediction - that if it continues to grow at the present pace, it could double today,” he warned. But “there would not appear to be imminent danger to another community.”

The situation remains highly worrying regardless, Goodale indicated. “It looks like the weather in and around Fort McMurray will still be, sadly, very conducive to serious burning conditions,” he said. “The situation remains unpredictable and dangerous.”

Alberta’s government crisis cell warned that fire conditions remained extreme in the province due to low humidity, high temperatures and gusty winds. Still, in a glimmer of positive news, authorities have recorded no fatalities directly linked to the blaze so far, the minister said.

In the latest harrowing chapter, police convoys shuttling cars south to safety through Fort McMurray - now a ghost town - resumed at dawn Saturday morning.

Making their way through thick, black smoke, the cars were filled with people trapped to the north of the city, having sought refuge there earlier in the week.

Police, wearing face masks, formed convoys of 25 cars, with kilometers (miles) of vehicles, smoke swirling around them, patiently awaiting their turn.

With elevated risk that something could go wrong, the convoys along Highway 63 were reduced in size compared to the previous day.

Those being evacuated - for a second time, after first abandoning their homes - had fled to an area north of the city where oil companies have lodging camps for workers.

But officials concluded they were no longer safe there because of shifting winds that raised the risk of them becoming trapped, and needed to move south to other evacuee staging grounds and eventually to Edmonton, 400 kilometers (250 miles) to the south.

Some 2,400 vehicles have so far been able to make it to safety.

Oil company Syncrude, one of several in the region, announced Saturday that it had shut down its facility 50 kilometers north of Fort McMurray due to smoke.

“In order to ensure the safety of our personnel and the integrity of our operations, we are taking all units offline in a safe and orderly manner,” it said. But “there is no imminent threat from fire.”

Security camera footage from the inside of one family’s home underscored the speed at which the blaze could overcome any stragglers. Thick grey smoke filled the living room within 30 seconds, while flames quickly ate away a wall.

Among the first evacuees to reach Wandering River, a hamlet about 200 kilometers south of Fort McMurray, Margarita Carnicero said she had feared for her life on the journey to safety.

“It was a terrible experience,” she told AFP, sitting in her dust-covered SUV alongside her teenage daughter Michelle. “I was afraid, but I tried not to show it (so as) not to frighten my daughter.” “With all of the smoke, the trip was hard on the lungs,” said Greg Stengel, an oil company employee who also joined the convoy.

The government has declared a state of emergency in Alberta, a province the size of France that is home to one of the world’s most prodigious oil industries.

Alberta has been left bone-dry after a period of unusually scant rainfall and unseasonably high temperatures.

More than 1,100 firefighters are battling 45 separate blazes across the province - six of them totally out of control, including three in and around Fort McMurray.

Oil companies crucial to the region such as Suncor, Syncrude and Shell have pulled out non-essential employees, and analysts said the three have slashed output by a total of a million barrels a day.

The cuts amount to around a quarter of the country’s entire production, and one-third of Alberta’s, and mean a loss of tens of millions of dollars per day in income.