The Royal Canadian Mounted Police said the victims were a 57-year-old man, a 50-year-old woman and a 47-year-old woman, the Canadian Broadcasting Corp. reported. They were all in the same vehicle.
The accident occurred on Highway 126 near Kent Junction, the CBC said.
"At this point, I can tell you the road conditions were very slippery and snow-packed," Sgt. Jeff Johnston told CBC News.
The lone occupants of the other two cars were hospitalized non-life-threatening injuries, he said.