Two people have died and four more were critically and seriously injured in a two-vehicle crash in Otago this afternoon.

Police this evening confirmed the deaths of two people at the scene of the collision on State Highway 1, between the intersections with Titri and Bungards Rds.

Emergency services were called at about 12.15pm.

Four more people were transported to hospital, three in a critical condition and one in a serious condition, police said.

The Otago Daily Times understands there are children among those involved in the crash.

A patient is readied for airlifting to hospital after the crash on State Highway 1 north of Waihola, Otago. Photo / Graeme Gale Helicopter Otago

A police spokeswoman initially said “reports suggest there are serious injuries”.

In an update about 1.45pm a Hato Hone St John spokesman said four people had been taken to Dunedin Hospital, three in a critical condition and one serious.

Police said they were called to the crash on State Highway 1, north of Waihola about 12.15pm. Photo / Otago Daily Times

Helicopters Otago pilot and chief executive Graeme Gale said the crash was “an absolute tragedy”.

 “I don’t know what caused it or how it happened, but there were two cars involved... and with extremely sick patients.”

Earlier, St John said three ambulances and two helicopters had been sent to the scene.

A witness who asked not to be named said she felt “traumatised driving past” about 12.30pm before emergency services arrived.

“I didn’t see it happen, but it looked horrific,” she said.

“I don’t know how it would have happened as it was right on the brow of the hill, so no one should have been considering passing.”

A Fire and Emergency New Zealand spokesman said three appliances, from Milton, Waihola and Balclutha were responding.

A reporter at the scene said traffic was being diverted down Titri Rd.

- Additional reporting by Otago Daily Times