A St John spokesman said two helicopters and two ambulances were at the scene.
A Hawke's Bay DHB spokeswoman confirmed two people were airlifted to Hawke's Bay Hospital in critical conditions. Both were women, one in her 20s and another in her 50s.
The spokeswoman said they received another crash victim, a male in his 50s, but did not have any status update on his condition as he was still being assessed.
A woman at the nearby hotel said a witness to the crash described it as a "head-on".
The woman said it appeared a car had drifted across the centre line into another vehicle, which was then hit by an oncoming truck.
She said that the person, who called emergency services, was "definitely shaken up".
"The car was right in front of them. It just veered across the centre line."
She said it made for a sad start to Christmas for all of those involved.
A Rangitaiki Tavern worker said occupants from a car who witnessed the crash rushed to their pub to use the phone to call emergency services.
The crash happened about 5km from the tavern and there was no mobile phone reception out there, she said, saying the eyewitnesses had come in looking frantic.
The worker was told by the occupants that the crash looked "extremely bad".
She could see the odd car still going past, but expected the road would be closed saying that, "There are quite a few trucks lined up."
The crash occurred less than an hour after police reopened SH25a at Kopu on the Coromandel Peninsula after a two-car fatal crash earlier on Monday.
Police were alerted to the crash around 9.10am and the road was closed for about four hours and reopened about 1.30pm.
