RCMP said the Maritime Bus motor coach landed next to a power pole on Route 2, near Summerside. Everyone escaped, but a few people were taken to the Prince County Hospital with minor injuries.
Many passengers waited at a nearby home until a smaller bus arrived to take them to Charlottetown.
Mike Cassidy, owner of the bus line, said the coach was blown off the highway by high winds.
"The driver explained it to us. The bus went over to the shoulder, nosed into the ditch and just kind of toppled onto its side," he told CBC News.
The accident happened at 5 p.m. AT as the second winter storm in a few days blanketed most of the Maritimes.
The storm was expected to hit Newfoundland and Labrador on Monday, with snowfall amounts ranging from 10 to 15 centimetres in southern Newfoundland to as much as 45 centimetres in eastern Labrador.
Parts of northwestern and southern Newfoundland were bracing for winds gusting from 100 km/h to 140 km/h.
Snow began late Saturday
Flurries first hit the western Maritimes late Saturday.
Environment Canada said the intense nor'easter brought nearly 40 centimetres of snow to parts of southern New Brunswick, while about 15 to 20 centimetres was forecast for Prince Edward Island by Sunday evening.
About 20 centimetres of snow was expected to fall in northern Nova Scotia and blowing snow warnings were issued for much of the province.
Meanwhile, people living in southeastern areas of Nova Scotia awoke to less snow than they expected. By mid-morning, the snow had turned into a wet mix of rain and ice pellets.
"It's pretty wet right now," said Charles Faleeni, shovelling the slush from his driveway in north-end Halifax. "It's not as much as what was called for."
The roof of a small warehouse in Dartmouth collapsed under the weight of heavy snow Sunday afternoon, but no one was hurt.
An official with the Halifax regional fire service said the building on Fairbanks Street was empty.
"It's a small warehouse and looks like it rotted through [with] water damage and had some kind of structural collapse due to the weight of the snow. It may be repairable, but it doesn't look like it," said Pat Kline, acting division commander.
Environment Canada ended the blizzard warning for Nova Scotia in the afternoon. However, Cape Breton and northern areas of the province were under wind and blowing snow warnings.
By Sunday evening, all of P.E.I. faced weather warnings for wind, blowing snow and storm surge.
People were warned to stay away from the shorelines and roads in Prince Edward Island National Park because of the high water and rough surf.
The Confederation Bridge was open to traffic except for high-sided vehicles.
In New Brunswick, winter storm warnings were in place for Moncton and northeast areas.
Slippery roads in all 3 provinces
Police urged motorists to stay off the slippery roads throughout the three Maritime provinces.
"If you are out and about there's the usual message of slow down, allow extra distance between vehicles and take your time," said RCMP Cpl. Scott MacRae. "If you do see somebody in trouble or the emergency personnel on the side of the road please give them a lot of space because they are trying to help anyone out there who may have slipped off the road."
There were a couple of accidents in Nova Scotia due to slippery conditions, but the RCMP said no one was seriously injured.
In New Brunswick, there were reports of drifting snow on roads around Sussex and Fredericton. Roads are snow covered through much of the south and eastern parts of the province.
"Hey, it's all good," said Paul Graham, shovelling in Saint John. "Take it in stride. We live in Canada."
Thousands affected by power outages
There were pockets of power outages in Nova Scotia throughout the day.
About 2,800 customers spent hours without power in Clare, Liverpool, Pubnico, Shelburne and Guysborough County. By late afternoon, there were outages in Bridgewater.
By Sunday evening, there were about 3,000 customers in the northern part of the province without electricity.
Nova Scotia Power said it brought in extra staff ahead of the storm to minimize the impact of the storm on the power grid.
Early Sunday morning about 3,000 customers in Moncton were in the dark. Most of their power was restored. By Sunday night, about 1,100 customers around the province were experiencing a power outage.
In P.E.I., about 200 customers were without power as of 9 p.m. AT., down from a height of 370.
Both the arrivals and departures boards at Halifax Stanfield International Airport were a sea of red Sunday morning. Many flights were cancelled or delayed. Airport spokesman Peter Spurway said the delays could continue into Monday and urged travellers to check on the status of their flights before heading to the airport.
Three departing flights and four arriving flights at Saint John Airport were cancelled Sunday. There were also a few flight cancellations and delays at airports in Moncton and Fredericton.
On P.E.I., the morning flight to Halifax was cancelled.
The poor weather also forced the cancellation of the Marine Atlantic ferry between Newfoundland and Cape Breton.
Bay Ferries cancelled its two runs Sunday between Saint John, N.B., and Digby, N.S.
Eastern Canada had just finished cleaning up after being blasted by another winter storm late last week.
Parts of New Brunswick were hit with between 20 and 38 centimetres of snow and in some places freezing rain.
That system then headed up to Newfoundland, where about 25 centimetres fell on the northeast coast and central parts of the island.