Lt. Jean-Francois Beauchamp of Gatineau police described the deaths as suspicious but refused to speculate on their cause.
Beauchamp said officers arrived at the residence, located in the city's east end, at around 7 p.m. Friday after receiving a 911 call.
"At that point, the three people were taken to Gatineau hospital where authorities pronounced them dead," he said.
Beauchamp wouldn't say whether the trio were related, though Cogeco News reported the victims were a couple in their 50s and their son in his 30s.
"It's too early to say exactly what happened inside the home," Beauchamp said.
"But right now, I can't confirm whether it involved a family dispute or a marital dispute."
Beauchamp said the 911 call came from a woman in her 20s who arrived at the residence, but he said her relation to the deceased wasn't yet known.
Neighbours told the local French-language newspaper Le Droit they hadn't noticed anything unusual at the home recently.
"We never expected anything like this to happen here," said Michel Vincent, who lived nearby. "It's a very quiet area."
Investigators remained at the scene Saturday, where they worked behind police tape that cordoned off the home.