MISSISSAUGA, Ont. - Ontario's police watchdog has cleared four Toronto police officers in the shooting of an 18-year-old man at a busy downtown subway station that sent commuters scrambling.

The Special Investigations Unit says it has concluded there are no reasonable grounds to charge the four with any criminal offence in connection with injuries sustained by the man in the Dec. 13, 2013 incident.

The SIU says the incident began when a man boarded a subway train with a black pellet gun that bore a "strong resemblance" to a pistol and ordered the other passengers off the train at Queen Station downtown.

It says the man wanted to spark a confrontation where police would kill him, and that officers repeatedly urged him to drop his weapon but that he didn't comply.

The agency says he pointed his gun at police, who shot at him, then stepped onto the platform and again turned his gun toward an officer, resulting in more shots fired and the man falling wounded to the ground.

Director Tony Loparco says the use of lethal force was justified because the officers as well as civilian witnesses thought he had a real gun.