Two people were trapped after an apparent head-on collision in Timaru.
A police spokesperson said there were five occupants in the cars, two of which were trapped.
St John spokesperson Ian Henderson said two patients with serious injuries, two with moderate injuries and one with minor injuries have been transported to Timaru Hospital.
Fire fighters have now freed the pair.
Police said all emergency services were in attendance at the crash that happened on the Timaru-Temuka highway between Arowhenua Station Rd and Arowhenua Rd.
"It appears to be a two-vehicle crash and it appears to be head-on."
A Fire Service spokesperson said fire fighters cut the occupants out of the car.
A St John spokesperson said they were called at 6.15pm. Two ambulances and a helicopter were sent to the scene.
There is a diversion in place at State Highway 1 and Dominon Rd and SH1 and Arowhenua Rd.
The serious crash unit is attending.