The entire population of the Canadian oil city of Fort McMurray was evacuated as firefighters battled an out-of-control wildfire that was likely to worsen Wednesday.
There were long lines on highways as 80,000 residents fled the blaze and oil sands work camps were pressed into service as emergency shelters.
"Apocalyptic" and "harrowing" scenes on social media showed vehicles facing thick smoke and raging roadside flames amid the largest evacuation in the province of Alberta's history.
"The city is under a complete mandatory evacuation order," Wood Buffalo municipality spokesman Robin Smith told NBC News early Wednesday, adding that an estimated 80,000 people had left the city.
He added that "20,000 have gone north to the oil sands camps that have opened their doors to house evacuees" while "35,000 residents have traveled south ... stopping for shelter in the communities of Anzac, Lac La Biche and Edmonton."
Smith said those people were being housed in "other industrial camp areas, as well as recreation centers and gymnasiums."
In the Beacon Hill neighborhood, 80 percent of homes have been destroyed, he added.
Firefighters from across Canada were being mobilized to aid in the fight.
The dangerous conditions that fueled the fire — high temperatures, low humidity and high winds — are expected to continue Wednesday.
"The worst of the fire is not over," warned Bernie Schmitte, wildfire manager at Alberta Agriculture and Forestry.
Burning debris fell into the paths of cars on roads out of the city as motorists tried to find their way through the thick haze.
"It became chaotic with vehicles trying to swerve and pull out into the ditch," said resident Jordan Stuffco, who described his drive out of the city as "harrowing."
Air tankers and helicopters buzzed overhead.
"[With] the heat from the oncoming smoke and the flames, you could see mini-tornadoes forming near the road," Stuffco added. "It was something out of an apocalyptic movie."
Northern Lights Regional Health Centre, the region's main hospital, said Tuesday night that all 105 patients, 73 of them in acute care units, were safely evacuated and were being transported to other facilities.
Twitter users reported that residents alongside one highway held up signs welcoming displaced citizens into their homes.
Fort McMurray isn't actually a fort — instead, it's a city along the Athabasca River. It was renamed from simply McMurray decades ago to honor its earlier history as a military installation.
Canadian Prime Minister Justin Trudeau tweeted that he was paying close attention to the situation.