Ontario's police watchdog is investigating after a 70-year-old man was fatally shot while Toronto police were executing a search warrant near Port Dover Wednesday afternoon.

The Special Investigations Unit said it happened at a residence in the area of Highway 6 and Highway 24 around noon.

Toronto police were executing a search warrant when shots were fired, the SIU said. A 70-year-old man was pronounced dead.

The agency said three investigators and two forensic investigators have been assigned to the case.

The SIU did not release further details about the incident, including what led to the shooting.

Toronto police tweeted Wednesday afternoon that one of their officers discharged their firearm, and one person was struck.

The SIU is called to investigate whenever police are involved in a death, serious injury, sexual assault allegations or the discharge of a firearm at a person.