Police are on the way to a crash involving a motorcyclist and a fence on the Shenandoah Highway (SH65) near Maruia in the Tasman District at about 8 am this morning.
Reports are that the rider has critical injuries.
A helicopter is on the way to the scene.
Motorists are warned that there will be delays while the scene is under examination.
This area is a communication black-spot, so further information will be released when more is known.