One person has died and 6 others injured, some seriously, in a horror crash on State Highway 1 at Spotswood in Hurunui.

A police spokesman said the crash involved several vehicles and happened around 4pm, just south of the intersection with Macmillan Road.

Chris Lynch Media understands at least three vehicles were involved.

The Serious Crash Unit was still at the scene four hours after the crash.

The road is likely to remain closed for some hours the spokesman said.

A St John Ambulance spokesman said eight vehicles attended and treated 6 patients and transported 5 patients to Christchurch Hospital.

Two patients were in a serious condition, two suffered moderate injuries and two suffered minor injuries.

Three helicopters, four ambulances, and an operations manager responded to the incident.

Motorists are asked to avoid travelling if possible or take the signalled diversions.