A 69-year-old woman was killed and her husband remains in serious condition after a deadly chain of events unfolded Thursday morning on Highway 1 west of Calgary.

Paramedics were attending the scene of a minor accident in the eastbound lane near Scott Lake Hill when they saw a silver SUV lose control in the westbound lane, cross the median and flip over.

The vehicle was spinning out of control when it hit an ATCO van, according to Cochrane RCMP.

The woman from Fort Macleod, Alta., who was a passenger in the SUV, was ejected and died on the scene.

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The 69-year-old passenger of this SUV died Thursday in a crash west of Calgary on the Trans-Canada Highway. (Courtesy of James Bundy)

A paramedic went to attend her husband, the driver of the SUV, who passed out as he was being examined.

EMS spokesman Adam Loria said the man's foot accidentally hit the gas pedal.

"The vehicle travelled a number of metres with our paramedic still inside the vehicle through the window," he said. 

"At that time his focus changed to his safety, and obviously the safety of the driver. He was attempting to either put that vehicle into park or somehow shut that vehicle's ignition off. At that point, there's no luck, he had to jump away for his safety."

The SUV then collided with an Alberta Sheriff's prisoner transport van. No prisoners were in the vehicle

STARS Air Ambulance airlifted the 72-year-old SUV driver to hospital, where he remains in serious condition.

The two sheriffs travelling in the van were taken to hospital by ambulance and are listed as stable in non-life-threatening condition.

Braden French says he was the first driver to hit a patch of black ice, which caused his truck to lose control and travel across the median into the eastbound lanes. Luckily there was no oncoming traffic at the time.

He said the SUV was behind him when it also crossed the median, striking two vehicles.

Both lanes of Highway 1 from exits 131 and 161 were closed to deal with the two collisions, but westbound lanes reopened Thursday afternoon. 

Eastbound lanes opened after 5 p.m. MT on Thursday, but drivers experienced delays for hours. Traffic was also being diverted onto Highway 1A to ease the congestion.

RCMP are still investigating, but say road conditions may be a factor.

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Firefighters with Redwood Meadows Emergency Services deal with a fatal accident on Highway 1. (Sarah Konsmo/CBC)