A massive explosion and fire ripped through the historic downtown core of Barrie, Ont. overnight, destroying several buildings and forcing the evacuation of dozens of people.

Firefighters fought for hours to extinguish the blaze, which broke out at 11:20 p.m. in a Thai restaurant located at Dunlop and Bayfield Streets.

A number of people in the community, located approximately 90 kilometres north of Toronto, heard the explosion. The blast occurred in the basement of the restaurant, scattering furniture and glass.

"Boom, everything just blew out the bottom windows," one Barrie resident told CTV News.

The fire quickly spread to neighbouring buildings and at least 50 residents from nearby apartments and patrons at a hotel were evacuated. The evacuees were provided shelter by the local church, Salvation Army and local hotels. One building collapsed in a flurry of flames and debris.

Dozens of firefighters from neighbouring communities rushed to the scene, pumping in water from Lake Simcoe to extinguish the blaze. One firefighter suffered a dislocated shoulder; however, no other injuries were reported.

One distraught downtown resident said she may have lost all her pets in the blaze.

"A dog that goes everywhere with me, two cats, two birds and two guinea pigs," said Rosemary Bonhamschriver, shaking and in tears.

Dozens of people who lived above the businesses have been left homeless.

Fire officials described the blaze as one of the worst in decades. At least six buildings were destroyed, among them the landmark Wellington Hotel.

Coun. Jeff Lehman told CTV Newsnet the hotel's destruction comes as a great loss to the city.

"It's the historic centre of the downtown. That is a great loss and there are some stores to the north and to the west that have also been gutted," he said Friday.

Eight businesses have been destroyed along the large block of buildings known as the Five Points Intersection. Fire officials estimate millions of dollars in damage has occurred.

Deputy Fire Chief Rick Monkman told CTV Newsnet on Friday that the fire has been contained and fire crews are trying to extinguish a number of hotspots.

"We've had to close down a number of businesses in the immediate area because the building structure is still in question. We could have further collapses up the street," he said.

Monkman said the age of the buildings was a factor that challenged fire crews.

"(One of the buildings) was over 100 years old. It was balloon construction and for firefighters that know construction, balloon construction is one of the hardest fires to fight," he said.

"Also, our water supply was taxed quite heavily in the downtown core."

Barrie Mayor Dave Aspden told Canada AM on Friday that the city will rally despite already sinking money into restoration projects in recent years.

"I'm sure Barrie will pull together and we'll see business back in the same location in time," he said.

Part of the downtown area will be closed for the day which will likely cause a "traffic mess," he said.

Aspden said there is no indication what caused the explosion. "I just know the Barrie fire crew and the adjoining fire departments that had to come in and help have done a terrific job," Aspden said.

There are over 600 property owners and business operators in historic downtown Barrie, which was established in 1814.

The massive fire was the second to strike a prominent Georgian Bay community in a week. Last Thursday night, a blaze erupted along the main strip at Wasaga Beach, destroying up to 70 per cent of the tourist area's businesses.

With a report from CTV's John Musselman