UPDATE 7.17am: State Highway 29 is closed following a serious crash.
Emergency services are attending the crash on SH29, Lower Kaimai.
Police were called to the scene at about 6.20am.
A police spokesperson says the crash only involves one vehicle.
"Inital indications are one person may be critically injured.
"The road is closed, with diversions in place through Old Kaimai Road."
Motorists are asked to avoid the area if possible.
The detour is not suitable for heavy motor vehicles and motorists are asked to follow directions of emergency services on site.