Three people are dead after an overnight stabbing in Ottawa, including a man who was shot by police, the province's police watchdog agency said Tuesday.

Officers responded to a home on Anoka Street after receiving a 911 call at 10:30 p.m. Monday in which emergency services were told someone was being stabbed and screaming could be heard, the Special Investigations Unit said in a statement.

When police arrived, they saw a man stabbing a woman on the street, the SIU said. Preliminary information suggests he refused to drop the knife so three officers fired shots and the man was struck, the SIU said. He was pronounced dead on scene.

The woman was also injured by police gunfire and she was taken to hospital with a non-life-threatening gunshot wound, the SIU said. Police then found the bodies of two other women nearby.

The Ottawa police homicide unit is investigating the stabbing deaths and the SIU is investigating the police-involved death of the man.

Investigators are working to confirm the identities of the man and woman who were shot by the police, the SIU said.