Mounties say 12 people have been sent to hospital following a series of highway collisions involving nearly three dozen vehicles east of Edmonton.
They say the cause is believed to be wildfire smoke and fog that created low visibility on Highway 14 near Sherwood Park.
The crashes involved about 34 vehicles, including four semi trucks.
RCMP say two people have life-threatening injuries.
Other drivers and passengers were taken by bus to a local recreation centre.
Roads in the area were temporarily closed as vehicles were towed away.