Ontario Provincial Police said only that two men are dead and a man and a woman were taken to hospital after a string of incidents. Officers first responded to a report at 5 p.m. ET Wednesday.
CBC News has learned a gunman opened fire at six different locations in Tamworth, including the post office, fire hall, two locations along County Road 15 and two area homes. Officers then shot and killed the man, CBC News has been told.
Overnight, yellow tape surrounded the post office, and two shell casings were seen on the pavement, according to a reporter with the CBC affiliate, CKWS.
Police said the two people in hospital have serious but non-life-threatening injuries.
They said Ontario's Special Investigations Unit has taken over the investigation. The SIU investigates all cases involving police where there is a serious injury, death or sexual assault.
Police have not offered any details about what led to the deaths and injuries, and no names or ages have been released. They did say they're not looking for any suspects.
Tamworth has a population of about 500 people. It's about 190 kilometres southwest of Ottawa.