Police in Canada’s capital, Ottawa, said they were investigating the deaths of six people including four children and two adults found in a house in the southern part of the city.
A seventh person was in hospital with serious, but non-life-threatening injuries.
Police were called to the home in the Barrhaven area at around 11pm on Wednesday.
A suspect was arrested quickly after that and police said there was no ongoing threat to public safety. It was not immediately announced how the victims died.
Ottawa Police Chief Eric Stubbs told local radio stations that police did not believe the deaths were the result of domestic or intimate partner violence.
But he said they were also still trying to determine the relationship between the suspect and the victims.
Mr Stubbs said it was a “very tragic scene”.
Neither the identities of the deceased nor the age or identity of the person in hospital have been confirmed.
Police said investigative teams remained at the site and asked anyone with information to contact the homicide unit.
Ottawa mayor Mark Sutcliffe called the news distressing for all of the city’s residents.
“I was devastated to learn of the multiple homicide in Barrhaven, one of the most shocking incidents of violence in our city’s history.”
Mr Sutcliffe said in a post on X, formerly Twitter: “We are proud to live in a safe community but this news is distressing to all Ottawa residents.”
