A teenage girl and a man have died after a double fatal crash on State Highway 3 on Saturday.

Police were advised of the crash at Kaitoke, south of Whanganui, just before 5am on Saturday after it appears two vehicles collided head on.

An 18-year-old female driver of one vehicle, and a 47-year-old male driver of the other vehicle died at the scene.

Helicopters from Wellington, Palmerston North and New Plymouth transported three passengers in a serious condition to various hospitals.

SH3, at Kaitoke, is expected to be closed for sometime as the Police Serious Crash Unit investigates the cause of the crash.

Details of the deceased will not be released until next of kin have been notified.