The most powerful tornado to hit the province in years swept through the southwestern Ontario town of Goderich Sunday afternoon, killing one person and devastating the picturesque community on the shores of Lake Huron.

Downtown businesses, century-old buildings and several churches lost their roofs and upper floors as the twister ripped through the town.

Images show downed power lines, trees and debris strewn across streets, while witnesses described cars being picked up and thrown like toys.

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Police identified the victim as Norman Laberge, 61, of Lucknow, Ont., who was working in a salt mine in the town when the storm hit.

At least 37 people have been treated for minor injuries and no one has been reported missing, said Ontario Provincial Police Insp. Bill Klym.

Randy Mawson of Environment Canada said the town was battered by winds of up to 300 kilometres an hour, considered an F2- or F3-level tornado.

The province hasn't seen a storm that powerful since 1996, he said.

Debris litters downtown Goderich after a tornado ripped through the southwestern Ontario town Sunday afternoon. (Geoff Robins/Canadian Press)

"This is the worst damage I've ever seen," said Mawson, who has been investigating storms for 36 years.

Herb Marshall, the owner of the Park House Bar and Restaurant, was on the third floor of the building with his wife when the storm swept through the town on the shores of Lake Huron.

"[The storm] came up the hill off the lake, by us to the north and just took everything with it," Marshall said. "I believe I saw a garbage bin up in the air going by.

"I've only ever seen this in the movies."

Goderich officials have placed the town under a state of emergency and cut off natural gas to the damaged areas.

Mayor Delbert Shewfelt asked residents to stay out of the downtown core.

Cassandra Phillips-Grande, 16, was in a coffee shop in the town square when the wind started to pick up.

"We saw tables and chairs outside of the cafe flying and then saw an SUV roll like a tumbleweed right in front," she said, adding that everyone in the shop moved to the back of the building.

"About two seconds later we heard this really big crash and the roof collapsed in the spot where we had all been. When we went outside we saw that some apartments had collapsed right in front of the cafe."

Phillips-Grande said she tried to help some of the people who were injured.

"We saw some people with gashes and one person had a brick fall on their head but no one was hurt too badly," she said.

Sean Carver watched the storm approach from his patio.

"The storm was quick, it blew through and it was gone," he said. "The so-called scary part is literally only about two minutes, half an instant, and then the winds go back down to about 80 kilometres an hour, but you know you're safe again."

He said residents are helping with the cleanup.

"We cleared out the streets ourselves, we just walked out there to get chainsaws and started clearing it," Carver said. "All you hear is chainsaws. There's tractors driving around because you can't drive anywhere.

"The town actually comes together and everybody starts helping everybody. There's kids walking down the street with hack saws, teenagers just helping anybody that needs help."

Donna Lovell, a waitress the Candlelight Restaurant and Tavern who has lived in Goderich all her life, said the storm struck quickly.

"We didn't see anything and then all you hear is sirens. From what I understand it sort of literally tore the town in half."

She said most of the destruction is in the area of Victoria Street.

"The roof of the church, I heard, is on the highway. There used to be a restaurant called the Burger Bar, there's no longer a Burger Bar," Lovell said. "I heard most of the [downtown] square has been damaged, all of the trees are down on the square — there's a lot of old trees up there. So there's major repairs, and they're not allowing anyone up on the square because there's a lot of gas leaks."

Candlelight owner Gus Balkouras said his business is without hydro, but otherwise unscathed.

"I feel terrible. Terrible, especially with the people who have damage up town and destroyed properties," he said. "Mother Nature sometimes, it's very difficult to predict what will happen."

Andrea Ross, who works at the Cedar Lodge Motel in Goderich, said the storm was the most violent she has ever experienced, as the skies became very dark with huge clouds.

"I've heard a lot of the buildings are half gone or fully gone," Ross said. "It's a pretty big mess downtown.

"A lot of buildings are missing and down and a lot of trees are down. I've heard there are gas leaks as well on the street behind us, so it's pretty bad."