Broken walls, windows and other debris fill a street damaged when an apparent tornado touched down Thursday on the edge of Durham, Ont. (Dave Chidley/Canadian Press)Violent thunderstorms and suspected tornadoes swept across southern Ontario on Thursday — killing at least one person, downing power lines and trees and ripping off roofs in several communities.

The death occurred in the town of Durham, police confirmed without giving details. A tornado reportedly touched down in the community, about 50 kilometres south of Owen Sound near Lake Huron and 180 km northwest of Toronto.

Multiple tornado sightings were reported across the province, including this one in Collingwood, Ont. (Submitted by Cathy Butler)Environment Canada meteorologist Geoff Coulson said at least three buildings in Durham suffered damage when the storm hit around 4 p.m. ET. Without confirming a tornado, the agency warned of potential twisters occurring through Thursday evening.

In the wake of eastbound storms that swept through the Greater Toronto Area, the City of Vaughan declared a state of emergency. The city just north of Toronto opened shelters for residents displaced from their homes.

About 120 seriously damaged homes in Vaughan had to be evacuated, said York Region Fire Chief Greg Senay.

The powerful storms overturned vehicles, lifted roofs off homes and pulled air conditioners out of windows.

The storm gradually lost some power as it crossed the eastern part of Ontario. Late Thursday night, the last tornado watches for the Kingston area were dropped by Environment Canada.

Severe thunderstorm warnings remained up for an area stretching from Pembroke to Ottawa and Brockville.

An estimated 69,000 Hydro One customers were reported to be without power in the wake of the storms, while Toronto Hydro said an unknown number of its customers were without power due to multiple outages.

Flights affected

The severe weather caused dozens of delays and cancellations at Toronto's Pearson International Airport.

"It's the same as any time we have a storm. It takes some time to come back to normal," Greater Toronto Airports Authority spokeswoman Trish Krale told CBC News, without elaborating on how many flights were affected.

Pearson has a policy requiring ground crews to be pulled from outside work when lightning strikes are recorded in the vicinity of the airport, she noted. "There was quite some time the ground crews were inside," Krale said.

Barn thrown

"It was a full-blown tornado, without any doubt," Durham-area resident Philly Markowitz said.

A barn on her property was picked up and thrown into her home, she told CBC News.

"The house directly across the road from me is missing a roof," she said. "The house next door to me — the barn is missing. We can't find the barn."

The town of Durham, Ont., about 60 kilometres south of Owen Sound, was reportedly hit by a tornado on Thursday afternoon. (CBC)Coulson said an unconfirmed tornado sighting was also reported in Craigleith, near Collingwood.

Possible twisters

A tornado reportedly hit near Vaughan Mills Shopping Centre, just north of Toronto, as a thunderstorm moved in a northeasterly direction, according to Environment Canada.

York Region police dispatched crews to the scene but didn't immediately confirm the presence of a tornado to CBC News.

The town of Milton, west of Toronto, also may have experienced a tornado.

"[It] looks like a tornado touched down here," resident Rod McLachlan said. "The roof is off a [former] church and a whole street is littered with branches broken off of trees."

Commuter Jane Taguicana told CBC News she was on a GO Train going toward Milton at around 7 p.m. ET when the train stopped for more than an hour. Passengers were told the train was delayed by fallen trees on the tracks, as well as signal problems.

The Toronto Transit Commission said a northern section of the Yonge-University-Spadina subway service was shut down from Downsview station to Wilson station. Shuttle buses were in service, the TTC said.

'The barn is missing. We can't find the barn.' —Philly Markowitz, who lives near Durham, Ont.

The town of Markdale, east of Durham, was also reportedly struck by a tornado.

"[They were] the highest winds I've ever seen in my life going by," Mark Worthington of True Value hardware in Markdale told CBC News.

"Trees were ripped down, 60-foot trees have been pulled out of the ground, we lost about a quarter of our roof and we have a barn outside and half of the roof is off of it as well."

Markdale's deputy mayor, David Fawcett, said the community's cemetery "has been hit really, really hard."

He estimated that 40 to 50 trees had been knocked down by the storm. Tombstones were also toppled, likely by the falling trees, he said.

Prime Minister Stephen Harper issued a statement, saying: "Our thoughts and prayers are with any who have [seen] loss of life or been dislocated because of this and obviously the Government of Canada, where appropriate, will work with local and provincial authorities to deal with the situation."

With files from The Canadian Press