Police identified the victims as 51-year-old Benoit Cote and 30-year old Marie-Josée Sills, who were shot around 6 p.m. Thursday in the cabinet of a Terrebonne, Quebec law office.
The shooting has been linked to the deaths of three men found just after midnight Friday in a home that had been set ablaze in Boucherville, just south of Montreal.
Longueuil police spokesman Tommy Lacroix said the bodies were likely those of a father and his two sons but he wouldn't confirm the information because the corpses had not been officially identified. He confirmed the deaths were possibly the result of a murder-suicide and were linked to the Terrebonne shootings.
Reports have speculated the father killed his sons before making his way to the Terrebonne law office to kill his former lawyer and an employee.
Various reports said the father in Boucherville had filed a $1.2-million lawsuit against a lawyer who was one of the two people shot in Terrebonne.
Police have not confirmed the circumstances surrounding the deaths, saying there were "points" left to clarify.
Lacroix said the timeline of events and motives behind the shooting had yet to be established. He said autopsies had been ordered.
"What we know up to now is that one of the people inside the house — one of the victims — seems to have left the house at night and when he came back set the house on fire before committing suicide," he said Friday.
Lacroix said investigators found a large quantity of fire accelerant in the home, leading them to believe the fire was set deliberately, "but that remains to be determined."
Police said it's too early to conclude a motive for the crimes but added they are not looking for any other suspects in the case.
A vigil for Gabriel and Jeremie Dubuc has been organized for Saturday evening in Boucherville.