One lane of the Eastbound 401 has been re-opened after a crash involving as many as 25 vehicles.
12 tractor trailers were reportedly caught up in the mess that happened around noon near Brighton.
Constable Peter Leon with OPP says there were whiteouts and slippery roads reported at the time of the crash.
He says injuries have been reported, but they are all minor.
Most lanes of the eastbound side of the 401 is expected to be closed for a number of hours, with the westbound side expected to be slower than normal, thanks to the visual distraction.
Leon reports there is snowsquall activity through that area continuing through the afternoon.