Ontario Provincial Police estimate 30-50 vehicles have been involved in separate collisions on the QEW east of Hamilton as whiteouts and icy roads create a treacherous stretch of highway.
Between Hamilton and Grimsby, multiple cars have been reported in collisions, according to Sgt. David Woodford.
"The worst I saw was a seven-car collision but we have probably 30 to 50 collisions on the go," Woodford said.
"Most of them are single vehicles that have gone into the guardrail, but we just keep seeing them come in one after the other after the other."
He said low visibility and slippery conditions are the culprit, and traffic is stalled in areas due to collisions, but the QEW remains open as of 4 pm Thursday.
A cold weather alert and snow fall warning were both issued for the area, with temperatures dipping to recorded at -28 C with the wind chill in Hamilton and up to 20 centimetres of snow expected to blanket the area throughout the day.
Along with fresh snow, fallen snow is blowing with wind from the northeast at 40 km/h gusting to 60 km/h, reducing visibility to as low as 400 metres.