The Greater Toronto Area was slammed by an ugly mix of rain, snow, strong winds and freezing temperatures Sunday that caused chaos on the roads and scattered power outages.

Earlier in the day, Environment Canada issued multiple weather advisories that covered much of southern Ontario, including watches or warnings for snowsqualls, rainfall, high winds and flash freezing.

The weather agency warned that in parts of the GTA and surrounding areas visibility on roadways could be "significantly and suddenly" reduced to almost zero due to heavy and blowing snow.

As the nearly 35 mm of heavy rain and rolling fog that hit in the morning turned to heavy snowfall and roaring winds of up to 85 km/h, Toronto police reported a flurry of weather-related collisions on city roads — including a six-vehicle crash near the intersection of McNicoll Avenue and McCowan Road and a TTC bus that slid off the road into a tree, injuring three.

Hello Winter. Be safe out there friends. <a href="https://twitter.com/hashtag/onstorm?src=hash">#onstorm</a> <a href="https://t.co/4IXItvIa3X">https://t.co/4IXItvIa3X</a> —@TPSChrisBoddy

To combat the icy conditions, the City of Toronto deployed 200 salt trucks and other de-icing equipment throughout the day. The preemptive work will pay off throughout the week, as temperatures are expected to remain in the sub-zero range until the weekend.

Ontario Provincial Police similarly warned that conditions on highways were deteriorating quickly, and asked drivers to stay home if travel was not essential.

A large branch of an old tree has come down on a house on Wineva Avenue in the Beaches. (Michael Cole/CBC)

There was also multiple incidents of downed trees and power lines throughout the city, resulting in power outages for more than 3,000 homes in the Mimico area and North York. To the northeast of Toronto, the entire town of Uxbridge lost power for hours due a Hydro One outage.

Some flights at Toronto Pearson and Billy Bishop airports were affected by the winter storm as well. Officials warned travellers to check the status of flights before leaving for the airport. You can check the status of any flight coming to or from Pearson here.

Police said three people suffered minor injuries when a TTC bus slid off the road into a tree on Lawrence Avenue. (Grant Linton/CBC)

In other parts of southern Ontario, Environment Canada upgraded snowsquall watches to warnings, with significant snowfall expected in the regions surrounding Lake Huron, south to Barrie and the Bruce Peninsula. Rainfall warnings were issued for southeastern Ontario, stretching from Peterborough and the Kawarthas to Ottawa, with up to 30 mm of precipitation possible in those regions.