A 26-year-old woman was killed after the driver of the car she was riding in lost control on Highway 20, east of the Ontario border.
Quebec provincial police said the woman, a Vaudreuil resident, was a passenger in a car driven by a man in his 20s.
Police said the car was travelling east at around 2 a.m. ET when the driver lost control, the car flipped and landed upside down in the ditch.
The driver suffered serious injuries, but his life is not in danger, police said.
Sgt. Daniel Thibaudeau said he could face charges in connection with the crash.
"Alcohol would appear to be a factor in this collision," he said. "Blood test will be done on the driver to determine his alcohol level."
One lane of the highway was closed as police continued their investigation.