PICKERING, Ont. -- Ontario's police watchdog says there are no grounds to charge a Durham regional police officer who shot and injured a teenager holding an imitation firearm.

The Special Investigations Unit says the incident occurred when an officer was responding to an armed-robbery call at a veterinary clinic in Pickering, east of Toronto, on July 16.

The agency says the officer was confronting a 17-year-old suspect outside the clinic when the teen pulled out an imitation gun.

The SIU says the officer gave several warnings and yelled at the teen to drop his weapon but when the teen began to point it at him, the officer fired eight times.

Two bullets hit the teen in the upper body and he was taken to hospital for emergency treatment for his injuries.

The watchdog agency says the officer was justified in firing because the fake gun didn't have a fluorescent tip as required by law, and there was no way to identify it as an imitation firearm.

The Special Investigations Unit is an arm's-length agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.