Two people have died following a serious crash on State Highway 1 near Redwood Pass this morning.

Emergency services were called to the two-vehicle crash at around 10.40am.

Despite best efforts by emergency services, two people died at the scene, a police spokesman said.

St John said it responded four helicopters, three ambulances, and two managers to the scene.

“Our crews assessed and treated three patients; two in a critical condition airlifted to Wellington hospital, and one in a critical condition airlifted to Christchurch hospital. Please refer to police for further information.”

NZTA said the road is expected to be closed for several hours while the crash is investigated, and the incident site is cleared.

Drivers must avoid the area until the incident is resolved.

Those travelling between Marlborough and Canterbury, including those with Picton ferry connections, should detour via the inland route: SH63 Wairau Valley, SH6 Kawatiri Junction to O’Sullivans, SH65 O’Sullivans to Springs Junction, and SH7 Springs Junction to SH1 Waipara.