No one was hurt, but a century-old building known to firefighters as "dangerous" has been destroyed after a five-alarm fire on Parc Avenue in Montreal's Plateau–Mont-Royal neighbourhood Wednesday morning.

A call reporting a fire at a four-storey building between Sherbrooke and Milton streets came in around 9:15 a.m. ET.

According to the Montreal fire department, the fire began on the second floor of the vacant R.S. Muir & Co. building, which was built in 1875.

Video from the scene showed huge clouds of smoke rising into the sky. As the wind shifted, the smoke started to drift down Parc toward downtown.

Fire in a building on Parc avenue in <a href="https://twitter.com/hashtag/montreal?src=hash">#montreal</a>. Smoke is getting thicker by the minute. Its in an old building. <a href="https://twitter.com/CBCMontreal">@CBCMontreal</a> <a href="https://twitter.com/JdeMontreal">@JdeMontreal</a> <a href="https://t.co/RQg0K36RV8">pic.twitter.com/RQg0K36RV8</a> —@momosalahi

Building of 'heritage interest', and 'dangerous'

The building is of heritage interest but did not have an official designation, according to a tweet by Mayor Denis Coderre.

The building was last inspected July 4 and everything was up to code, Coderre said.

Its open walls and floors allowed the flames to spread quickly, said fire department spokesman Ian Ritchie.

The building also had a lot of old, flammable wood inside.

Le <a href="https://twitter.com/MTL_SIM">@MTL_SIM</a> estimé que du Parc/Milton sera fermé jusqu'en soirée. Prévoyez une rentrée à la maison difficile dans ce secteur <a href="https://twitter.com/hashtag/rcmtl?src=hash">#rcmtl</a> <a href="https://t.co/22VJGgLiQB">pic.twitter.com/22VJGgLiQB</a> —@pascalrobidas

Speaking to reporters Wednesday afternoon, fire chief Martin Farmer said the building was a known fire hazard and fire inspectors had taken an inventory of its contents.

"This one was really noted because of the combustible materials inside," Farmer said.

"There was an accumulation inside this building that wasn't usual, which is why its contents were inventoried. We knew that if there was ever a fire, it would spread quickly into a major fire."

As a result, Farmer said the building was considered potentially "dangerous" to firefighters in the event of a fire, but he said there was no danger to the public.

The building is usually barricaded, but squatters have been known to break in. It is unclear whether anyone was inside Tuesday night or Wednesday morning.

Asked if the city was managing its vacant, historic buildings properly, Coderre said the city and its inspectors are "doing our job."

"We're doing what we have to do," he said.

"But we'll wait for the inquiry."

DERNIÈRE HEURE Montréal: Important incendie en cours avenue du Parc près de Milton. <a href="https://twitter.com/hashtag/rcmtl?src=hash">#rcmtl</a> <a href="https://t.co/mKUhxYJWEP">pic.twitter.com/mKUhxYJWEP</a> —@SMCharronRC

The fire spread to roof of a neighbouring brick building that houses the Alto restaurant but the flames were extinguished there. Windows above the restaurant were blown out. A sign outside says the restaurant was established in 1987.

Important incendie sur avenue du Parc (coin Sherbrooke) 5e alerte 100 pompiers sur place. Évitez ce secteur. <a href="https://t.co/ouBw5bHdMr">pic.twitter.com/ouBw5bHdMr</a> —@DenisCoderre

Three families were forced to leave the building and the restaurant was also evacuated.

One of those forced from his home was McGill University law student Mike Glasz.

He said he always thought the old Muir building next door was "really beautiful" and got a tour of it two years ago.

"It wasn't in the best of shape but it looked really beautiful," he said, adding that one of the rooms he saw was full of 30 or 40 classic arcade games.

"A lot of beauty and history was lost in this fire."

The old R.S. Muir & Co. building dated from 1875. The fire that destroyed it also heavily damaged the building on its left housing the Alto restaurant. (Google Street View)

More than 120 firefighters were called to battle the blaze. Dozens of trucks lined the street as they worked to put out the flames.

The operation was made more complicated by low water pressure in the area, Ritchie said.

The cause of the fire is still unknown and the investigation has now been taken over by the Montreal police arson squad.

Heavy equipment has been called in to tear down the historic building's exterior, which is unstable and now also considered dangerous.

Parc Avenue remains closed between Sherbrooke and Milton streets and could remain closed until Thursday morning.

Neighbourhood around Place des Arts filled with smoke from fire on park near Milton <a href="https://t.co/7dsGdUjZYK">pic.twitter.com/7dsGdUjZYK</a> —@s_dubreuil

The fire comes less than a week after a historic building went up in flames in Chinatown.