A spokesman acknowledged that the chances of finding the group alive had dimmed, but police were “keeping up hope” of recovering their bodies.
The search for the snowmobilers includes divers, sonar operators and police backed by helicopters in the area about 225 kilometers (140 miles) north of Quebec City, and is expected to resume again at daybreak.
Quebec provincial police spokesman Hugues Beaulieu said the body discovered Friday “was found more than two kilometers from the initial search area in Grande Decharge River” at the mouth of Lake Saint-Jean where the accident happened.
“At the moment, we can't identify the body,” French Consul General in Quebec Laurent Barbot said during a press briefing. “The process is underway and the families have of course been informed,” he added.
The group included eight French tourists, who were snowmobiling Tuesday evening in an area that is off limits to snowmobiles because the ice is thinner there.
Three snowmobilers survived with minor injuries. They returned to France on Thursday evening, according to the consulate.
Their 42-year-old Canadian guide died on Wednesday in a hospital after trying to rescue members of the group.
Police have recovered six snowmobiles at the bottom of the lake near where the accident occurred, and provincial authorities have pledged to tighten safety measures on the use of the machines.
Investigators do not know why the group left the approved paths to venture “off-piste” at nightfall, but some experts believe they may have been trying to take a shortcut to their destination.