(CNN) A manhunt is on in Canada after two men detonated an improvised explosive device, injuring 15 people late Thursday inside a restaurant in Mississauga, Ontario, near Toronto, police said.

"There's no indication this is a terrorist attack. There's no indication this is a hate crime," Peel Regional Police Chief Jennifer Evans said during a Friday morning news conference. "At this time, we haven't ruled anything out as we start our investigation."

The suspects walked into the Bombay Bhel Indian restaurant in the city outside Toronto around 10:30 p.m. and detonated the device, police said. They then fled, police believe, in a vehicle, Evans said.

Surveillance photos show the men wearing jeans and dark-colored hoodies. One had his face covered with a black cloth, police said.

Two parties, including a birthday celebration, were going on at the restaurant at the time of the blast, Evans said.

It's not clear whether those patrons were targeted, she said, adding they included children younger than 10.

'They need to be brought to justice'

Mississauga Mayor Bonnie Crombie called the explosion a "heinous crime" and said she was thankful no one was killed.

"This is certainly not anything you would expect to happen in Mississauga, not my Mississauga, this is not the Mississauga I know," Crombie said Friday. "Certainly, the people who have done this need to answer for their crimes, and they need to be brought to justice."

Twelve of the injured had been released from the hospital by Friday morning, Evans said. Those still being treated at a Toronto trauma center include a 35-year-old man and women, ages 48 and 62. Their injuries were critical, officials had said earlier.

The injuries were "consistent with those of an explosion," said Brian Gibson, deputy chief at Peel Regional Paramedic Services.

The restaurant by Friday morning had been deemed safe from any other explosives, Evans said, adding that the site sustained a "considerable amount of damage."