Cancelled trains, slow-moving traffic, and hundreds of vehicle accidents greeted Toronto commuters Monday morning as the first real dose of winter created havoc.

Freezing rain and snowfall warnings were issued for much of southern Ontario with most areas experiencing either snow, freezing rain or both.

GO Transit riders faced morning delays and cancellations as freezing rain caused rail switching systems to malfunction.

Motorists on the city's highways were greeted with snow-covered roads, slippery conditions and hundreds of crashes during the morning commute.

"I usually take my car but I looked out there and I wasn't going to chance it, so I hopped the bus," commuter Loretta Numminen said.

But even Numminen's bus was delayed.

"So now we have to wait."

To combat icy roads, Toronto's 200 salt trucks left works depots at 2 a.m. Monday morning. It was a sudden rush of activity for city employees who had been sitting idle for weeks into the start of winter.

"The crews are excited to go out and show the citizens of Toronto that they're ready to make the roads safe and passable for them," Manager of Road Operations Myles Currie said.

Despite best efforts, Mother Nature prevailed and drivers still had to navigate slippery 400-series highways.

Three cars were involved in a morning collision on Hwy. 400 near the Holland Marsh, prompting the Ontario Provincial Police to tell drivers to slow down.

"One hundred kilometres an hour is just plain foolhardy in this sort of weather," Sgt. Cam Woolley said.

"We're reminding people too with SUVs and four-wheel drives, while you have improved traction, the laws of physics are working against you. If you get going to fast, the vehicle is going to be difficult to turn or stop and quite easy to overturn."

By noon the OPP had responded to about 300 accidents on provincial highways. That number increased to 600 by evening and did not include accidents which occurred in GTA communities.

"Unfortunately, this is roughly what we predicted (in advance of the storm)," Woolley said. "The first storm (with) a lot of folks out of practice, not prepared with themselves or their vehicle and this is what we get."

On the highways, motorists were surprised by the sudden blast of winter.

"I did not listen to the reports," one driver said. "It caught me with my pants down."

School bus service was also cancelled in most districts east of Toronto, in the London area, and across eastern Ontario.

At Pearson International Airport workers frantically tried to de-ice aircraft, but not fast enough to avoid a backlog of flights. More that 50 flights were cancelled, mostly to Canadian and U.S. destinations, while plenty of others were delayed.

Travellers were advised to call ahead to check their flight status before heading to the airport.

The east-bound storm was expected to bring storm watches and snowfall warnings to the Maritime Provinces, starting Monday afternoon.

"Later this week, we're going to see clearly some cold air arrive to eastern Canada," Environment Canada senior climatologist David Phillips told Canada AM Monday morning.

"It's beginning to look like winter and it's going to feel like winter over the next couple of days."

Philips said the storm finally brought the long-anticipated end to warm temperatures most of eastern Canada had been enjoying.

"This is typically, across Canada, the halfway point when probably we can say there's more winter behind us than ahead of us. But for some of us in the East, it's just arrived -- much later than normal."