Police responded to dozens of accidents on highways in southern Ontario on Wednesday morning after an early blast of winter weather created slick roads and reduced visibility.

Temperatures hovered around the freezing mark overnight, creating a dangerous layer of ice on roadways. Flurries were reported in the traditional snow belt areas.

Some of the worst driving conditions were reported in the Barrie area along Highway 400, north of Highway 89.

A major accident on Highway 401 in Pickering, at Whites Road, shut down all westbound collector lanes during the morning commute. Police said there were serious injuries in the 5 a.m. crash, which involved several vehicles.

North of Toronto, a full-sized van ended up on its side after it spun out on Markham Road, near Highway 407. The passengers were shaken up, but not seriously hurt.

Toronto escaped the wintry weather conditions.

With files from CTV Toronto and The Canadian Press