Two were transported from the scene by ambulance to Whanganui Hospital Prior to the arrival of the Palmerston North Rescue Helicopter.
The third patient, a Whanganui man in his 20's, was airlifted to Palmerston North Hospital with serious head and leg injuries.
State Highway 3 at Kaitoke is expected to be closed for some time as the Police Serious crash unit carries out an investigation into the cause of the crash.