Police believe six people involved in a serious crash near Kurow in South Canterbury on Saturday night were not wearing seat-belts.
They were in a Land Rover travelling along Hakataramea Valley Road just before midnight, when the driver lost control and the vehicle roilled several times.
Three people remained in Christchurch hospital, one in a serious condition, one was in Timaru hospital, and two were airlifted to Dunedin hospital.
Sergeant Mike van der Heyden said it appeared no one was wearing a seatbelt , as all of them were thrown from the car.
He said police were also investigating whether alcohol was a contributing factor to the crash.