Sel Gras, a Mediterranean restaurant that opened just a week ago on St-Laurent Boulevard near Fairmount Avenue, was ravaged by the blaze.
The restaurant was owned by four young people in their twenties and thirties.
"We got a call this morning around I think it was 5 a.m., that the place was burning down," said co-owner David Martin.
"We opened last Tuesday. A Mediterranean restaurant which we had been working on for quite some time now. And that's it — a week later we're done."
The windows were shattered as firefighters fought to control the blaze. It's since been extinguished, but inside remains only charred tables and chairs.
Const. Daniel Lacoursière of the Montreal police said the arson squad will investigate the scene later this morning to try to determine the cause of the fire.
"When the fire department got on the scene, indeed there was a fire in the restaurant," he said.
"The investigator of the Montreal fire department was called on the scene. After examining the scene, he determined that he didn't know what the origin of the fire was."