Tons of snow crashed into a school gym in Kangiqsualujjuaq, Quebec, a coastal village 950 miles north of Montreal on Ungava Bay, off the Labrador Sea.
"It was a little after midnight, when 400 to 500 people were in the village gymnasium, when the avalanche struck," said a Montreal police spokesman. Ten of the injured were in a "serious" condition.
Rescuers searching for the three missing people in and around the gym feared another avalanche and the roof caving in. Villagers dug frantically through the tons of snow that slid down the 250ft hill in an effort to find the missing, said Luc Harvey, chief of the Kativik regional police force in Kuujjuaq,190 miles to the west.
"They are getting tired, they have been working all night," he said. "But they are not giving up."
The 600-member Inuit community in the Ungava Bay region has only one doctor and two native police officers.
Military and provincial police attempting to get more personnel into the area were hampered by a fierce storm, but one aircraft with 15 emergency workers managed to get through. It was due to fly the most seriously injured to the nearest hospital in Kuujjuaq. Two other planes carrying more police officers and search dogs were also en route.
The village, which used to be known as George River because it lies at the mouth of the river, was established in 1838 as a Hudson's Bay Company trading post. Kangiqsualujjuaq means "very big bay".