State Highway 2 is closed - and will be for most of the day - after what police will only describe as a "serious incident".

The incident happened early yesterday evening between Kerepehi and Ngatea and police say they will release more information in the next few hours.

The State Highway is closed between Orchard East Road and Wharepoa Road.

Heavy trucks are being asked to use alternative highways such as State Highways 1, 27 and 29 where possible.