A postal worker struggles as he climbs a hill against a headwind soon after Friday's storm hit Toronto. (Robin Rowland/CBC)

The snowstorm that pummelled Toronto all day Friday sparked hundreds of accidents, delayed hundreds of flights and forced the city to shut down several services.

GO Transit, which moves about 200,000 passengers on a normal weekday, cancelled several late afternoon and early evening routes because of the winter storm, which blanketed Toronto with roughly 20 centimetres of snow before tapering off in the evening.

GO said it was cancelling some departures and rescheduling some trains on its busy Lakeshore line. It is also asking passengers to be prepared for delays on its bus routes.

GO said it took steps just before noon to try to deal with the expected delays during the evening rush hour.

Elsewhere, the Toronto-bound Queen Elizabeth Way in Hamilton was expected to be closed for several hours after a tractor-trailer jackknifed Friday evening at Burlington Street and spilled its load. The Ministry of Environment sent personnel to the scene to begin the cleanup operation.

As of Friday evening, Ontario Provincial Police had reported more than 260 accidents and said the highways in southern Ontario were verging on impassable because of whiteout conditions.

"It just looks like a wrecking yard with all the vehicles that have been brought in that have damage done to them," Sgt. Dave Woodford told CBC News from the scene of one of the day's accidents.

The most serious accident was reported north of Toronto, where at least five people were sent to hospital with serious injuries after a chain-reaction crash on southbound Highway 400.

Tractor-trailer jack-knifes

The incident began around 11 a.m. when a tractor-trailer jack-knifed, causing several vehicles to pile into one another, provincial police said. None of the injuries was considered life-threatening.

Toronto police asked people to stay off the roads and drive only if necessary.

"Snow does not cause collisions. Speed, driver error, distraction and inattentive operation of vehicles causes collisions," police warned in a release distributed Thursday night.

In another development, the City of Toronto closed its municipal services at 2 p.m.

"Due to the current weather conditions, all city offices, including city hall and civic centres, will close at 2 p.m.," a news release issued Friday said.

The one exception was city-run child-care centres.

"City of Toronto child-care centres will remain open until such time as parents are able to pick up their children. Staff will remain at child-care centres until all children are picked up," the release said.

Included in the closures are community centres, recreational and swim programs, and drop-in programs.

The city said it would do its best to have facilities open on Saturday.

Emergency declared

On Friday morning, the city also declared an extreme cold-weather emergency, which frees up additional resources to help Toronto's homeless.

In preparation for the storm, some regional school boards cancelled bus service, but schools remained open.

Bay Street was closed off by Toronto police at the height of the tempest after glass began falling from an office building. (Robin Rowland/CBC)

Commuters trying to get in and out of the city were given ample notice of the incoming weather system — and the lighter than normal morning rush hour was an indication that many heeded the warnings and took an extra day off.

The Toronto Transit Commission put its snow plan in effect, bringing in extra equipment aimed at keeping the uncovered stretches of the subway lines cleared.

On the roads, the city had its army of snow-clearing vehicles out in force. The main focus was on keeping main roads clean, followed by secondary roads and back streets, said Peter Noehammer, Toronto's director of transportation services.

"After the afternoon rush goes through and a significant amount of snow has fallen, then we'll send the plows out to all the local roads. [We'll] wind up cleaning them up tonight and overnight, into tomorrow," he said.

Delays, cancellations at Pearson

At Pearson airport, the country's busiest, the storm caused more than 350 delays and cancellations throughout the day as crews tried to keep the runways clear.

On Thursday, both Air Canada and WestJet made the unusual move of advising passengers travelling in and out of Pearson that they could book earlier or later flights without penalty, depending on availability.

The airport, which handles about 80,000 passengers on an average day, is expected to see more than 100,000 each day during the holiday season.

Trish Krale, spokesperson for the Greater Toronto Airports Authority, said a lot of snow will inevitably bring flight delays and cancellations.

"The best advice is … check on the status of your flight before you come out here so you're not sitting in snowy traffic or trying to navigate through the airport and then find out when you get here that there's a situation with your flight," Krale said.

The snow problems are expected to continue through the weekend.

On Saturday night, another storm is scheduled to arrive.

"We're looking at the snow arriving late Saturday night," CBC meteorologist Karen Matthews said, "from the southwest to the Golden Horseshoe, and including Georgian Bay. With the Sunday storm … we're looking at around 10 to 20 centimetres, probably more on the lower end of that for the GTA and high amounts up and through the typical snowbelt areas."