A section of downtown Toronto's historic Queen Street West neighbourhood was destroyed Wednesday morning as an intense blaze gutted several buildings, tearing through businesses and leaving dozens without shelter.

The fire remained a six-alarm blaze for hours but was eventually downgraded to a five-alarm incident by the late afternoon.

At its height, 150 firefighters and 56 fire trucks were on the scene battling the blaze as it burned out of control in frigid temperatures that hovered at about -20C with the wind chill.

Three addresses on Queen, just east of Bathurst Street, have collapsed, Toronto Fire Services spokesperson Capt. Adrian Ratushniak told CTV.ca. The area is a popular shopping district.

"It looks like 623, 625 and 627 Queen St. have collapsed," said Ratushniak in a morning telephone interview from the scene. "They have been completely flattened. There are no longer any buildings there."

Fire officials said they were afraid other buildings would also crumble.

The power has been turned off for a couple of blocks in the area for fear that crumbling buildings could bring down electrical wires.

No injuries have been reported as a result of the blaze. But some people are reportedly being affected by heavy smoke in the area, and one street south of the affected area has been evacuated.

Some residents sought shelter at the nearby Trinity Community Recreation Centre.

Just after 5 a.m., emergency crews were called to a fire inside a building that houses National Sound, an electronics store at 615 Queen St. West, near Portland Street on the south side of Queen.

Ratushniak said fire officials still don't know if that's where the fire started.

When firefighters arrived on the scene they found people living in the upstairs apartments of the affected buildings "hanging out their windows," Ratushniak said. All were eventually rescued by emergency workers with ladders.

By 2 p.m., fire crews were still trying to put out flames smouldering under layers of debris.

Freezing conditions and slippery streets made it a challenge for crews to fight the fire as water froze to ice as soon as it hit the ground and the building.

'Won't be the same'

Jessica Milton, a resident who lives in the Queen and Bathurst area, said she saw the owner of Duke's Cycle standing amongst the crowd that gathered to watch the fire. She and a few others approached him to express their sympathy after learning the store was in the building that crumbled.

According to the shop's website, Duke's has been around since 1914 and has been owned by the same family for generations.

"When I went up to him to express my sympathies, all he said was, 'We'll be back,'" Milton told CTV.ca.

Later in the day, co-owner Gary Duke told reporters he was trying to remain positive despite the circumstances.

"Everyone got out, that was the great side of this story," Duke said.

"We'll regroup. I'm not going to stop now after 94 years. We'll find another space ... and probably rebuild the building. That's my immediate (plan).

"My season is just starting and I have good relationships with my suppliers and I think everything will work out, it's just going to be a real struggle."

Milton said she's a regular customer at the cycle shop and was proud that it and others small businesses along Queen were part of her neighbourhood.

"That's what drew me to the neighbourhood," she said. "The fact that they might not be there anymore....it definitely won't be the same."

Businesses and apartments between 611 and 627 Queen Street were affected by the fire. Other businesses impacted by the blaze include Nikolaou Restaurant Equipment, Suspect Video, Preloved, Pizzaiolo, Jupiter, Cosmos Records and several others.

The daughter of the owner of National Sound said her 65-year-old father has owned the business for the past 40 years and now has nothing left.

"His whole life, the last 40 years -- documents, paper work, banking information -- everything is gone," she told CTV Toronto. "He's 65 years old, I honestly don't know what he's going to do."

The neighbourhood was just recently declared a heritage district and had managed to avoid being included in a large residential and retail development planned for the area.

Milton said when she stood near Queen and Bathurst she couldn't smell the smoke though it covered the area. It was only when she was walking to work along King Street towards John Street that the smell "hit her like a ton of bricks," she said.

"It was overpowering, I could barely breathe."

Traffic rerouted

Traffic, including streetcar service, was rerouted around the area. Ratushniak said the fire has brought down several electrical wires in the area but couldn't say for sure if TTC streetcar wires had been affected.

He did say that the area would be closed off for most of the day as officials investigate the scene and crews clean up the debris.

The Fire Marshal's Office has been notified of the fire and will investigate, but officials said it was way too early to determine what caused the blaze or if it was sparked under suspicious circumstances.

Division commander Bob O'Hallarn told reporters "we may not know for a long time how the fire started."

The area is being treated as a crime scene until the source of the fire is determined, officials said.

Damage from the blaze could top $10 million, authorities said.

Ratushniak said six-alarm fires are rare but that it was declared today because of the number of personnel and resources needed to fight the difficult fire.

With reports from CTV Toronto's Austin Delaney and Roger Petersen