Two people — a man and a woman in their late 40s — were found shot to death in a home in Drummondville on Monday evening.
The investigation then led police to the town of Asbestos where there was a standoff with an armed man in his 60s. Police say he committed suicide as they negotiated with him.
"The investigation is ongoing and detectives will try to determine what transpired," said Const. Daniel Lacoursiere, a Montreal police spokesman.
Montreal police were called in to take over what had originally been a provincial police file. In Quebec, it is customary for another police force to investigate when someone dies or is hurt during a police intervention.
Provincial police were first dispatched to the Drummondville home after receiving 911 calls reporting gunshots.
The 46-year-old woman was found dead inside, while the 49-year-old man was found on the back balcony in a quaint new residential project.
The investigation quickly led police to Asbestos, east of their crime scene, where a 63-year-old man armed with a gun held police at bay in the parking lot of a bar.
Talks between the man and police lasted nearly four hours, until early Tuesday morning.
"While negotiating with the individual, the man turned the gun on himself at about 2 a.m. and his death was confirmed by doctors at the hospital," said Montreal police Const. Simon Delorme.
Lacoursiere said it's too early to say what the link is between the two victims and the man who committed suicide.
The motive behind the slayings isn't entirely clear yet.
"All this will be part of the investigation," Lacoursiere said.
Police have not confirmed the identities of the victims.