Torrential rains and widespread flooding throughout southern Alberta on Thursday washed out roads and bridges, sent residents scurrying for safety and delivered up surreal scenes of cars, couches and refrigerators just floating away.
The RCMP put out a call for help to the Canadian Armed Forces, which sent in two helicopters and a Hercules aircraft to help extract people stranded by water.
Officials with the City of Calgary said as many as 100,000 people in low-lying neighbourhoods could be forced from their homes due to heavy flooding, an evacuation that would take place in stages over the next few days.
Bruce Burrell, director of the Calgary Emergency Management Agency, said water levels on the Bow River aren't expected to subside until Saturday afternoon.
"Depending on the extent of flooding we experience overnight, there may be areas of the city where people are not going to be able to get into until the weekend," he told a news conference.
Burrell said they suggested workers in downtown Calgary, which borders on the river, leave work early Thursday if they live in threatened areas, so they could prepare to evacuate.
Other workers were advised to consider staying late so as to lighten the rush-hour load on roads that might be needed for evacuations.
Evacuees were being asked to stay with friends or relatives, though recreation centres were being set up to accommodate those who had no place to go.
The Calgary Zoo, located on St. George's Island, shut down in the afternoon and said it would also be closed today.
"Rest assured Animal Care are working closely with our facilities team to ensure the safety of all of our animals during this period of flood risk and are following our established emergency protocols," the zoo said on its website.
The Bow River Basin was battered with up to 100 millimetres of rain.
There were flashpoints of chaos from Banff and Canmore and Crowsnest Pass in the Rockies, to Calgary and beyond in the north and south to Lethbridge.
"I woke up at about three o'clock in morning to the sound of this kind of rumbling and it was the creek," said Wade Graham, a resident of the mountain town of Canmore, west of Calgary.
"At first it was just intense, pretty powerful, amazing thing to watch. As daylight came, it just got bigger and bigger and wider and wider, and it's still getting bigger and bigger and wider and wider.
"All you can hear is like boulders and trees. I watched a refrigerator go by, I watched a shed go by, I watched couches go by. It's insane."
The flooding was particularly destructive in communities just south of Calgary such as High River, Turner Valley and Black Diamond, where the Highwood River swept away two people.
"One female adult had been stranded on a trailer and also a second adult male had been stranded on a nearby flatbed," said Cam Heke of STARS air ambulance.
"We did respond to the area. The female adult was no longer on the trailer and was missing. We did conduct a search along the river and we were unable to locate that missing person.
"However, the male adult was on the trailer and local emergency services with another helicopter organization... were able to rescue that man."
In High River, the water trapped residents in their cars and forced others to flee to the rooftops of their homes.
Streets became tributaries, swamping vehicles.
Randy Livie said he came into town to help a friend and almost didn't get out.
"It was over my hood," he said. "There was a jeep in front of me and he stalled out. There was a minivan that went in front of me. He stalled out. This other car, he came in and he started floating away -- he bailed out. He had crutches. A truck pulled up and helped him out. It's just wild down there."
-- The Canadian Press