This truck was one of the vehicles involved in the 20-car pileup on the eastbound lanes on the Highway 401 near Woodstock. (David Ritchie/CBC)
Ontario Provincial Police are at the scene of a 20-car pileup in the eastbound lanes of Highway 401 near Woodstock, Ont.
OPP said they aren't aware of any serious injuries, but ambulance and fire services on are on the scene.
The highway is shut down from the 401/403 split in Woodstock all the way to Kitchener. OPP said it would be closed well into the evening because as many as 12 tractor-trailers were involved in the pileup. At least 40 vehicles not involved in the crashes are stuck in the area.
The pileup occurred near the Drumbo Road exit ramp, OPP said.
The cause of the crashes has not been determined.
"Outside of people not driving according to road and weather conditions, that would be the early indicators of what happened," said OPP Sgt. Dave Rektor.
"But we'll have to wait until the OPP technical collision investigators arrive on scene and make a more educated determination."
Wednesday's late-winter storm dropped an estimated 10 to 25 centimetres of snow in areas across southern Ontario, creating tricky travelling conditions.
GO Transit has temporarily suspended Hamilton QEW express service and announced 90-minute delays on several other routes, including Waterloo Highway 401 service, University of Guelph and Oakville Highway 403 service.
Police initially reported that up to 60 cars were involved in the pileup. That number has since been revised to 20.