The QEII Highway south of Edmonton has reopened after a series of crashes that injured 100 people during a storm that dumped as much as 25 centimetres of snow on Thursday.

The aftermath of the chain-reaction crashes closed the highway — the main route from Calgary to Edmonton — until late Thursday night. About 85 to 100 vehicles were involved in the crash near the town of Millet.

About 80 people were treated at the scene by EMS and another 22 were taken to area hospitals.

RCMP said that the most seriously injured person was a man who was struck by a semi-truck while he was standing outside his vehicle after a collision.

About 45 heavily damaged vehicles had to be towed. The CBC's Briar Stewart reported that most of the vehicles have been cleared away. She said the road is open but slippery.

RCMP investigators are trying to piece together what happened. Since the scope of the crash was so huge, RCMP Corp. Colette Zazulak said that collision reports were not filed at the scene the way they typically are.

Once people file reports with RCMP detachments, investigators hope to get a better picture.

"Which ones happened where, and what vehicles were involved," Zazulak said. "From there, they're going to determine whether it was just nature, in the sense of the conditions, or whether there are any charges to be laid or things like that."

Another crash north of Edmonton killed a 23-year-old woman, a four-year-old girl and a two-year-old boy.

They were in a car that crashed head-on with a truck about 85 kilometres north of Westlock on Highway 44.

Three others were seriously injured, including the driver of the truck, who is facing charges including dangerous driving causing death.

Within Edmonton, city police dealt with 133 collisions on Thursday, nine involving injuries.

Edmonton cleanup crews worked overnight to clear streets in time for the Friday morning commute.