TORONTO -- Ontario's police watchdog says there are no grounds to charge any Toronto police officers involved in the shooting of a 40-year-old man last December.

The Special Investigations Unit has determined that police were justified in shooting the man after he advanced on them wielding a 13-centimetre knife in a Walmart parking lot.

The investigation found that the man, a Walmart employee, had been harming himself with the knife after he grew distraught during a meeting with loss prevention officers about his suspected theft of store items.

The SIU says police first tried persuading the man to drop the knife, then drew their guns and finally fired three shots when he continued closing in on them.

The man was taken to Sunnybrook Health Sciences Centre for treatment.

The SIU is automatically called in when there is a death or serious injury involving police.