EDMONTON -- Terrified passengers on a Thursday morning Red Arrow bus got a front-seat view of the icy multi-vehicle Highway 2 crash that left 100 motorists with mostly minor injuries.

"Cars were flying beside us in ditches," said Derek Fildebrandt, Alberta director of the Canadian Taxpayers Federation, who was on the bus headed for Edmonton when the pileups unfolded before his eyes.

"I looked up and saw 18-wheelers slamming into one another, cars flying beside us into the ditches. Our bus driver slammed on the brakes and we just watched this massive pileup developing in front of us."

Fildebrandt was working on a speech he was to deliver at the University of Alberta Thursday night when he glanced up from his laptop around 11:30 a.m.

Soon after, police shut down the long stretch of Highway 2 northbound, north of the Highway 13 overpass. Mounties said one crash triggered others and the total vehicle count was more than 100.

Alberta Health Services spokeswoman Sharman Hanatiuk said Edmonton-area hospitals treated at least 100 people, 80 of whom had been tended to by emergency crews at the scene.

One patient was transported by ambulance to the University of Alberta hospital with serious injuries, five were transported to hospital with "moderate" injuries, and 14 others were treated in hospital for minor injuries.

A "multi-casualty" incident bus, or a mini emergency room on wheels, was dispatched to the scene, Hanatiuk said.

Edmonton Transit buses were used to transport those with minor to moderate injuries to hospitals in surrounding communities, including Leduc, Fort Saskatchewan and Red Deer. Those without injuries were taken by bus to Wetaskiwin.

A pair of Edmonton police officers escorted the buses full of patients, said spokeswoman Leila Daoud, adding that officers with the Disaster and Emergency Operations Services branch remained on standby.

A code orange, or mass casualty event, was also enacted for Alberta hospitals, but was eventually stood down.

After the pileup, Fildebrandt walked up and down the highway to see if he could be of any help to those caught in the wreckage, as vehicles littered the snow-whipped road for "as far as I could see."

"Some people were pretty dazed but a lot took charge. Really impressed with how everyone reacted," he said. "It was a good example of citizens stepping up to the plate before first responders arrived."

Photos on Twitter show cars and semi-trucks scattered like toys along the highway, many intermingled with one another.