Businesses in the Plateau are on high alert as the Montreal police arson squad is investigating a suspicious fire that tore through Dusty's diner on Sunday night.

A mainstay of Park Ave. since its first pancakes were flipped in 1949, the fire broke out around 8 p.m. While the 60 firefighters on the scene were able to quickly extinguish the flames, accelerants were discovered.

"I don't have any description of what type of accelerant could have possibly been used," said Montreal police spokesperson Raphael Bergeron. "We know that an odour came to the fire department when they went inside the restaurant."

Damage to the greasy spoon was extensive, with the windows and glass doors blown out by the flames. In the rubble, some wooden benches were still visible the next day.

Investigators have confirmed that the fire was started near the restaurant's front windows.

"The owner of the restaurant didn't receive any threats," said Bergeron. "The investigation was transferred to us to try to determine what happened and why they were targeted."

Melanie Des Lauriers was working at her neighbouring business when she saw the flames rising from Dusty's. She was worried about losing her business.

"There were a lot of tears and we just had to wait and see," said Des Lauriers. "Now I feel some relief and we feel grateful that the business is fine."

While investigators have no leads at this time, the arson squad has been an overworked part of the Montreal police, dealing with a rash of firebombings that damaged restaurants throughout the island in 2011.

Whether the restaurant is rebuilt is unknown, but to fans of Dusty's it will remain an institution.

"There are definitely a lot of people that have come through that have worked here, that have strong connection to the place," said Rebecca Lessard, a former employee. "All our friends ate here and we came here all the time, just like a real neighbourhood spot. It's sad to see it go."

No one was in the restaurant at the time and damage to the building's second and third floors was minimal.