The crash occurred early Saturday in Notre-Dame, New Brunswick, the Canadian Broadcasting Corp. reported. The victims, three 18-year-olds and a 17-year-old, were all from the Cap-Pele area, a community of about 2,300 people.
Royal Canadian Mounted Police said the teens were in a car that left Highway 115 shortly after midnight, hit a culvert and rolled several times.
The deaths prompted the cancellation of a formal Christmas ball at the high school that serves the Cap-Pele area. Grief counselors were made available for students and flags at the school were at half-mast.
"It's tough," Emilie O'Brien said. "We grew up together, and seeing one of your best friends go is really hard.
"Just the smallest things can happen so fast. Now they're gone and you realize that life is precious and we've got take care of each other and be careful."
Cap-Pele Mayor Debbie Dodier said members of the community were gathering to mourn.
"Right now, the whole municipality is in shock," she told the CBC. "It's four families that lost their child, but there's more families that are touched by it."
The RCMP said three of the victims were not wearing seat belts and were ejected. All four died at the scene.
Police said speed was a factor in the accident.