It comes just a month after 25-year-old Alek Minassian killed 10 people and injured 15 more in a bloody van rampage in the city.
The injuries have been described as "penetrating trauma injuries", according to Jeremy Cohn, a reporter on the scene.
"At this point there is a very heavy police presence," he said, adding that tactical, K9 and explosives disposal units were also present. Firefighters have pulled back as police search for more possible explosive devices.
A witness who was inside the restaurant at the time, who wished to remain anonymous, told Global News he was inside when he heard a "big blast".
"I was in the bathroom with my kid, so I came out and everybody's hidden there," he said.
The first hooded figure is described as male, 5'10-6 feet, stocky build, mid-20s, light skin, wearing dark blue jeans, dark zip up hoodie pulled over head, baseball cap with light grey peak, face covered with black cloth material.
The second hooded figure is described as male, 1.77m-1.82m, fair skin, thin build, faded blue jeans, dark zip-up hoodie hood pulled over head, grey T-shirt, dark coloured skate shoes, face covered.
Police say they are looking for the public's assistance in identifying the parties that fled following the explosion.
The cause of the explosion remains unclear but it is believed the blast occured at a Bombay Bhel restaurant, a local Indian eatery.
Pictures of victims in multiple ambulances being transported to local hospitals have been captured by TV networks.
There are as yet no confirmed reports on casualties.
