Nelson Live has received reports of a vehicle collision at the lower end of the Buller Gorge Road near Westport leaving two vehicles rolled over.
Five people are reported to be trapped and traffic has been disrupted on State Highway 6.
The driver of one car is believed to be suffering a serious leg injury.
It is understood a rescue helicopter is on its way to the scene as well as rescue units from Nelson.
A tracking beacon has been activated at the site.