Police said they were advised of the crash, on State Highway 6 near Morris Rd, shortly before 2pm.
A Hato Hone St John spokeswoman said one person was airlifted to Dunedin Hospital with serious injuries. Two others had moderate injuries - one was taken to Dunedin and the other to Lakes District Hospital.
Three other people were treated at the scene for minor injuries.
The road was blocked for a time, but NZ Transport Agency Waka Kotahi advised about 3.20pm that it had reopened.
Motorists were advised to take care while travelling through the area.