One of the vehicles involved in a fatal Highway 7 crash Saturday just west of Stittsville, in Ottawa's far west end, was moving towards an emergency turn-around on the road just moments before the crash, Ontario Provincial Police said.

The crash claimed the life of Claudette Clement, 67, from Quebec, while her 63-year-old sister Monique beside her -- not wearing a seatbelt -- was airlifted to hospital and remains in critical condition. Another sister in the car, as well as the driver, were taken to the Ottawa Hospital, Civic Campus in an ambulance.

Police said a green 2010 Toyota Camry, driven by Pierre Duval, 66, from Quebec, was driving westbound on Highway 7 near Hazeldean Road with three passengers, including another one of Claudette's sisters, Yolande, in the front seat. The car moved onto the paved shoulder and then began to turn left towards an emergency vehicle turnaround.

Driving behind the vehicle was a 2009 Hyundai Elantra, driven by David MacDiarmid, 31, from Ottawa. It struck the Camry on the left side; police say the collision could not be avoided. The man was also taken to the Civic Campus by ambulance.

Highway 7 was closed until about 7 p.m. in that area on Saturday as traffic investigators looked at the scene.

Police thanked the numerous motorists who stopped on the side of the road to help the injured, and remind the public to wear seatbelts and to not to use the emergency turnarounds on the highways.

Alcohol was not a factor and names are being withheld pending notification of family members. Police said they would have more information on Monday.