A police spokesman said it was notified about 12.30pm of a crash involving a single vehicle on on Forfar St, in Maryhill, about 12.30pm.
No road blockages were reported, he said.
A St John Spokeswoman said an ambulance and a rapid response vehicle responded to the scene.
One patient was in a serious condition, she said.
An Otago Daily Times photographer at the scene said it appeared the car had rolled down a bank and onto private property.