A person has been critically injured in a crash in Harewood this morning.

A police spokesman told chrislynchemedia.com emergency services responded to a single vehicle crash on State Highway One near Mcleans Island Road at 6:50AM.

The was blocked as of 8.30AM.

A St John spokeswoman said they were notified of a motor vehicle incident and responded one ambulance, one rapid response unit, one first response unit, and one manager to the scene.

Crews assessed and treated one patient who was transported to Christchurch hospital in a critical condition.

NZTA said the Serious Crash Unit was at the scene and their investigations could take several hours to complete.