Emergency services were alerted to the crash off Palmer Rd in Springs Junction at 9.20 this morning.A St John spokesperson said they sent one first response unit and two helicopters to the scene.
One person is in a serious condition and one is in a moderate condition, they said.
State Hightway 7 Springs Junction to Reefton is currently closed. A spokesperson for the NZTA said motorists should consider delaying their journey.
A Fire and Emergency NZ spokesperson said the car went over a steep bank in dense bush and crews were attempting to rescue the two occupants of the car at 12pm.
A specialist lines rescue team is on its way from Christchurch by helicopter, they said.