Emergency services were called to the intersection of Kennington Rd, Kennington Roslyn Bush Rd and the Woodlands-Invercargill Highway (State Highway 1) about 3.30pm today.
A reporter at the scene said a blue utility truck and a white SUV collided.
Firefighters had to use the jaws of life to cut free the driver of the extensively damaged truck.
A Hato Hone St John spokeswoman said two people were taken to Southland Hospital - one critically hurt and the other with moderate injuries.
Two ambulances and two rapid response vehicles attended.
The serious crash unit was also at the scene.
State Highway 1 was closed between Kennington Rd and Longbush South Rd for a time but had since reopened.