Four people were taken to hospital with serious injuries, two by helicopter and two by ambulance. RNZ's Tracey Neal was at the scene.
To embed this content on your own webpage, cut and paste the following:
<iframe src="https://www.rnz.co.nz/audio/remote-player?id=201834775" width="100%" frameborder="0" height="62px"></iframe>
for easy access to all your favourite programmes