Three people are dead, including the suspect, after a man stabbed a woman and her two daughters before being shot by police in a hail of gunfire that also struck one of the victims.
Ontario's police watchdog said Ottawa police received a 911 call from a home on Anoka Street near Grasmere Crescent, just south of Heron Road, to report that someone had stabbed someone else.
It was about 10:30 p.m. ET.
"Screaming could be heard" during the 911 call, Special Investigations Unit (SIU) spokesperson Monica Hudon said Tuesday. The independent agency investigates deaths involving police, as well as serious injuries, allegations of sexual assault and incidents in which police fire weapons at people.
Ottawa police officers arrived at the house on Anoka and saw a man stabbing a woman in the road near the house, Hudon said.
Deaths in Alta Vista
Suspect, stabbing victim shot by police, SIU says
When the 21-year-old suspect did not drop his knife, three of the responding officers fired their weapons and killed him, Hudon said.
The 19-year-old woman he had been stabbing was also shot and was taken to hospital for treatment, she added.
The bodies of the two other females were found nearby. Police have not publicly identified the victims.
Neighbours say the home at 1273 Anoka St. is owned by a woman with two daughters.
Noella Buenti told CBC News she heard gunshots and saw the suspect's body lying on the road. She also said she spoke to the boyfriend of one of the stabbing victims.
"He was very upset and wouldn't talk. He just said there's someone with a knife. And the police asked him to put down the knife and he wouldn't. And then they shot him," Buenti said.
3rd victim still in hospital
The third victim remains in hospital with "multiple serious stab wounds," Ottawa police said Tuesday. She was in serious condition with injuries considered not life-threatening when she was taken to hospital, according to Ottawa paramedics.
Paramedic spokesperson Marc-Antoine Deschamps called the scene "complex." The area is about six kilometres south of Parliament Hill.
"I never thought it would happen in this neighbourhood, that's all. Life has gone crazy," Buenti said.
"It was unbelievable. I don't know how many police cars were here; it was over 10, 12 police cars; an ambulance, everything."
In a statement, Brian Samuel, interim president of the Ottawa Police Association (OPA), called the events of Monday night a "call for service with a tragic result ... which will have a lasting effect on our members and the community as a whole."
Samuel said the OPA is supporting the officers who were involved in the call.
"These are the difficult calls that don't happen often, but when they do, our officers respond in a professional manner, and do what they are trained to do," he said.