St John Ambulance have confirmed six people have been injured as a result of a two-vehicle crash on State Highway One at Orari north of Timaru.
Emergency services were called to the scene on the stretch of road known as the Canterbury Pacific Highway at 3.40pm.
Police say the crash was reported to be between a car and a campervan.
St John Ambulance spokesperson Ngaire Jones says four people have suffered serious injuries with two further people suffering moderate injuries.
Two of the seriously injured patients have been driven by ambulance to Timaru Hospital.
The other two seriously injured patients were airlifted to Christchurch and Dunedin respectively along with the remaining two patients.
The road was closed with diversions in place while emergency services attended.