Two people have died and another person is in critical condition after a two-car crash near Blenheim.

Emergency services were called to the crash on State Highway 1 near Redwood Pass at around 10.40am.

Hato Hone St John said it responded with four helicopters, three ambulances, two managers and a Major Incident Support Team vehicle.

Two people were airlifted to Wellington Hospital while the third was taken to Christchurch Hospital.

NZ Transport Agency Waka Kotahi (NZTA) said the road is closed to all traffic, with no local detours available.

“Travel between Marlborough and Canterbury is affected today following a serious crash on State Highway 1 south of Blenheim this morning.

“The highway is closed to all traffic following a car‑versus‑car crash near Cloudy Bay Drive – no local road detours are available."

The Serious Crash Unit has been informed.

Motorists are advised to expect delays or avoid travel if possible.

A spokesman from nearby Riverlands-based business Tinto Containers said there’s a long line of traffic being turned away by emergency services.

“By the looks of it they’re [drivers] not being allowed to continue south on State Highway 1. It’s blocked off just before the turn off to Redwood Pass Rd.”

The spokesman said it wasn’t uncommon to see emergency services scream past the area.