The NZ Transport Agency confirmed that SH79 has been closed between Geraldine-Arundel Road and McKenzie Street in Geraldine while police investigate the crash.

A St John spokesman said they responded to the scene with an ambulance and rapid response vehicle, but referred media enquires to police.

Motorists are advised to avoid the area and use alternative routes NZTA said.

Detours have been established for For light vehicles: Northbound traffic should turn right onto McKenzie Street in Geraldine, continue onto Orari Station Road, then rejoin SH79 via SH1. Southbound traffic should follow the reverse route.

For heavy vehicles: Northbound traffic is being redirected via Inland Scenic Route 72, then onto SH1 and back onto SH79. Southbound traffic should follow the reverse detour.

State Highway 1 (SH1) remains open.

The Police Serious Crash Unit was the scene at 11AM, to conduct an investigation into the crash.