Travellers heading north out of Christchurch towards Nelson are being told to take State Highway 1, due to a serious crash.
Emergency services are at the scene of the crash on Weka Pass Road, in Canterbury.
A police spokesperson says the three-vehicle crash happened near State Highway 7 in Hurunui, at 12:10pm.
The crash has closed the road north of Loop Road.
Road users should expect significant delays or delay their travel until it has been cleared.