The crash occurred at 7.05pm at the intersection of Dundas and Cumberland Sts.
Senior Sergeant Craig Brown, of Dunedin, said a Nissan Primera being driven on Dundas St "ran a red light", colliding with a south-bound Isuzu 4WD towing a trailer, causing them to jack-knife.
A Toyota station wagon then hit the Nissan, ending up on the footpath, while the Primera hit a traffic light stand.
Snr Sgt Brown said the 48-year-old Dunedin woman driving the station wagon was taken to hospital with a neck injury, which was believed to be serious.
The five occupants of the Primera - the 18-year-old male driver and two female and two male passengers - were not badly hurt and the male driver and a female passenger of the Isuzu were uninjured. Inquiries were continuing.
A St John spokesman confirmed the four patients were taken to Dunedin Hospital with minor to moderate injuries.
