Police are actively hunting for two suspects believed to be behind an explosion that rocked an Indian restaurant west of Toronto, sending 15 people to hospital, the chief of the investigating force said Friday.

Jennifer Evans of Peel Region police said the investigation into Thursday night’s blast at the Bombay Bhel restaurant in Mississauga, Ont., is still in its early stages, but said the incident is not currently believed to be either a hate crime or an act of terrorism.

“This is a really serious investigation,” Evans said Friday morning at a news conference just outside the plaza where the restaurant was located. “We want to take our time, make sure we’re very methodical in it. So we’re putting a lot of resources into this right now.”

Police said there was no information to suggest there was a threat to public safety, noting that they believed the blast was an isolated incident.

The two suspects believed to be behind the blast walked into the restaurant, located near Hurontario Street and Eglinton Avenue, around 10:30 p.m. on Thursday as two separate groups were holding birthday parties, Evans said.

The hoodie-clad men were seen carrying an “improvised explosive device” at the time and then fled the scene in an unidentified vehicle, Evans said.

N/R-Peel Police-Restaurant Explosion in Mississauga – https://t.co/KmWyEZVvMw pic.twitter.com/ZM4IjZwi8D

— Peel Regional Police (@PeelPoliceMedia) May 25, 2018

The resulting explosion injured 15 people ranging in age from 23 to 69, Evans said, adding they were taken to three different hospitals in the area.

While three of those injured — a 35-year-old Brampton man, a 48-year-old Mississauga woman, and a 62-year-old Mississauga woman — were originally listed in critical condition, Evans said they had since been upgraded to stable. The other 12 victims have been treated and released, she added.

Evans said children under the age of 10 were present at the time of the explosion, though none of them were hurt.

The presence of youngsters was particularly shocking to Mississauga Mayor Bonnie Crombie, who said the brazenness of the incident resonated with her as a mother.

“It is a heinous, reprehensible act, committed by cowards who would come into a restaurant where people are vulnerable, celebrating with their families, where children are present,” Crombie said, visibly shaking as she spoke. “Whoever has committed this heinous act needs to answer for their crimes and be brought to justice.”

Related: A third explosive device discovered on same road in Kamloops

Related: Improvised bomb injures 22 on London subway train

The area outside the plaza remained taped off early Friday morning as police continued the investigation. Officers were also examining a scene a few hundred metres away, looking at footprints in a new residential development.

Evans said the restaurant sustained significant damage in the explosion, though none was visible from the outside. She did not offer details as to the makeup of the explosive device or where exactly it was detonated.

Andre Larrivee, who lives in a nearby condominium building, said he had been watching television on Thursday night when he heard an explosion.

“It was really loud,” he said, comparing the noise to an electric generator that had exploded at a nearby construction site recently.

Christian Lanctot, who lives across the street from the scene of the explosion, said he heard sirens on Thursday night but thought nothing of it at the time. He learned of the incident while reading the morning news.

“I think that a lot of people are maybe just a little frightened because of the unknown factor of ‘what was the motivation,’” Lanctot said.

Police have released photos of the two suspects and urged anyone with information to come forward. Peel region officers are working with the RCMP and forces from around the Greater Toronto Area as the search for the men continues.

Crombie said the Indian Consulate General has set up a hotline for those impacted by the blast and has been in touch with her directly, but said the names of the victims have not yet been released.

India’s minister of external affairs, Sushma Swaraj, tweeted about the blast, saying she was in touch with the Indian High Commissioner in Canada and the Consul General in Toronto about the incident.

The leaders of Ontario’s three main political parties, all in the midst of an election campaign, issued statements of sympathy and solidarity for those affected by the blast.

“We are all shocked and saddened by the news out of Mississauga,” Liberal Premier Kathleen Wynne wrote on Twitter, adding she expected a briefing on the incident later in the day. “Our thoughts are with the victims and their families, and our thanks go out to the first responders.”

— with files from Michelle McQuigge in Toronto.

Liam Casey , The Canadian Press

Like us on Facebook and follow us on Twitter.