Emergency services arrived at the Glen, at the intersection of Glen Rd and Haywood St, at 5.05pm. Firefighters used the jaws of life to rescue people trapped in a car.
Fire and Emergency New Zealand assistant area commander Craig Geddes said appliances were sent from Lookout Point, St Kilda and Dunedin Central. Crew freed five people from the car.
St John spokesman Gerard Campbell said six people were taken to Dunedin Hospital by ambulance.
Two of them were in a serious condition and four people had moderate injuries, he said.
A witness at the scene, who was driving in Glen Rd, said they saw one of the cars involved coming down Haywood St before it went through the intersection, crossed both lanes on Glen Rd and crashed into a bank near their car.
"It was terrifying. Imagine if we were a little bit sooner, that could have been us."
The witness also believed the other two cars involved were travelling in opposite directions on Glen Rd, in line with the Haywood St intersection.
Another witness said they came out of their house after hearing a big bang but did not see how the accident happened.
Police were still at the scene investigating about 8pm.
There was traffic management in the area and the serious crash unit had been notified, a police spokeswoman said.
