Ontario Provincial Police say they responded to more than 800 calls for help from people on roads Sunday due to icy roads and blowing snow causing reduced visibility in southern Ontario.

Many vehicles all over the GTA spun out of control into ditches, and there were multivehicle collisions, but no one was seriously injured.

Sgt. Dave Woodford told ctvtoronto.ca that the hundreds of calls were made within the GTA, and the area of cottage country stretching from Peterborough to Orillia.

"With heavy snow falls, snow squalls, icy road conditions, visibility is poor. There are a lot of people coming back from vacation or skiing, so there's been a lot of traffic, and as a result there's a lot of crashes," Woodford said.

He said the OPP does not yet have numbers as to how many crashes occurred.

The OPP advised those who didn't need to be outside, to avoid the roads.

"Give the MTO a chance to clear the highway," Woodford said.

"It's very treacherous right now. Icy conditions, you name it. Crashes are just one after another," he said.

Police say there is black ice on parts of Highway 400 and the Queen Elizabeth Way.

Highway 26 in Simcoe County was closed due to near-whiteout conditions, while Highway 402 northeast of London was also closed due to poor weather.

Woodford said people should call ahead to their destination before going out, because events may have been cancelled.