Emergency services were still working to retrieve the car on Thursday morning after the crash about 11pm near the Victoria Park car park and Dyers Pass Rd intersection.
Summit Rd remains closed around the crash scene and walking tracks in the area are were also closed on Thursday morning.
St John spokesman Gerard Campbell said three patients were treated and taken to Christchurch Hospital, one in critical condition, one in serious condition and another in moderate condition.
He referred questions about the fatal crash to police.
It is understood the car went 3m down a bank.
Fire and Emergency New Zealand spokesman Darryl Ball said three crews attended the incident from the Governors Bay, Spreydon and the Christchurch City stations.
Crews had to extricate one person from the vehicle.
- Sophie Cornish
