As the SUV she was travelling in sank into the fridgid waters of an Alberta reservoir, a middle-aged woman was able to pull herself out and reach the safety of the shore.
Three others travelling with her weren't so fortunate. Despite a rescue attempt by passing motorists, they perished in hospital shortly after they were freed from the sunken vehicle.
The incident unfolded around 3:30 p.m., about 20 kilometres south of the mountain resort town of Canmore.
A Ford Escape was travelling along a dirt and gravel road when it left the street, crashed through a sheet of ice and into the Spray Lakes Reservoir.
One woman pulled herself to safety and made her way back to the road, where a passerby picked her up and drove her to hospital in Canmore. Other motorists waded into the waters and pulled two more people out of the vehicle, which lay on its side, completely submerged in six feet of water, said Canmore fire chief Todd Sikorsky.
They performed CPR on the pair until EMS and firefighters arrived. Emergency workers pulled the last person, who was deeper down in the back seat, out through a window.
The good Samaritans who tried to rescue the trio may have been off-duty firefighters from Calgary and mountain guides, Mr. Sikorsky said.
"We would never advise someone to do that, but it would be up to them to make an assessment of the situation," said RCMP Sergeant Tim Taniguchi of the daring rescue attempt.
All three were taken to hospital, where they were pronounced dead.
Police have not released the names of the dead, nor where they were coming from or going to, but said two were men and one a woman. Fire officials said they were in their 40s or 50s.
The two deceased men who were taken to hospital were to be airlifted to Calgary, said STARS air ambulance spokesman Cameron Heke. "Unfortunately, those patients died at the hospital," he said.
The woman who rescued herself is in hospital in stable condition.
Spray Lakes is west of Calgary, just outside the boundary of Banff National Park, and has an adjacent campground.
Thursday's incident marks the second grisly collision in the province in one week.
On Christmas Eve, a car carrying three young adults and a baby lost control and swerved into an oncoming vehicle northeast of Edmonton.
The three adults died, but the eight-month-old infant survived.