Police attended, along with St John and Fire and Emergency New Zealand.
The road was blocked for about half-an-hour, and northbound traffic was diverted into St Andrew St.
A bus tried to make the left turn but scraped the side of a police car which was helping to direct traffic.
A witness said it appeared that a takeaway delivery driver had gone through a red light and that vehicle was hit by another car.
A St John spokeswoman said one patient with moderate injuries was transported to Dunedin Hospital.