Quebec provincial police are investigating, after a 33-year-old woman was killed and her partner was seriously injured early Thursday morning in a home in Mascouche, about 45 kilometres northeast of Montreal.
There were children inside the home at the time of the incident, police say, but they were not injured.
Police have confirmed the woman's identity as Jaël Cantin, who was a mother of young children.
"We have a lot of possibilities. We don't know exactly what happened," said Sûreté du Québec spokesperson Sgt. Eloïse Cossette.
"Every hypothesis is on the table."
Police say someone called 911 at around 4 a.m. to report that people were injured inside a home near the intersection of Des Anglais Road and Raymond Boulevard.
Cantin and her male partner were found on the scene with serious injuries and were rushed to hospital, where the woman was later pronounced dead. The man is expected to survive.
The Sûreté du Québec major crimes unit has taken over the investigation and has set up a command post in front of the home.