A truck driver has been critically injured in a serious crash on State Highway 23, in Waikato.
Emergency services were called to the area - between Te Pahū and Waitetuna Valley Rd - about 8.30am after reports of a crash.
A northern fire communications spokeswoman said they were told the truck had rolled.
Four fire trucks were called out and the driver was extricated just before 9.30am.
St John said one person was taken to Waikato Hospital in a critical condition.
Transport authorities closed part of the road just before 9am.
The latest update, released at 9.40am, said: "Due to the serious nature of this crash, this section of SH23 (to/from Raglan) is likely to remain closed for quite some time today."
Motorists are being told to allow extra time for the detour.