A person has died and another is seriously injured following a two-vehicle crash on State Highway 1 at Seddon last night.

A police spokesman said the crash happened about 8.15pm, between Redwood Pass Road and Awatere Valley Road.

The drivers were the sole occupants of the vehicles and one died at the scene.

State Highway 1 reopened about 3.30am.

The Serious Crash Unit is investigating the cause of the collision and Police are providing the families with support at this difficult time, the police spokesman said.