A motorist travelling on the road, who did not want to be named, said she came across the scene when she noticed a car with its hazard lights on, on the opposite side of the road from the crash.
Another motorist was at the scene and administering CPR to the woman.
Ambulance crew arrived and also performed CPR on the woman.
Masterton Fire Service station officer Garry Nielsen said it appeared one person had been thrown out the back window, and the other through a passenger window.
The couple were taken to Wairarapa Hospital. Life Flight Westpac Rescue helicopter crew member Julian Burn said the man was then airlifted to Wellington Hospital. He was reported yesterday to be in a serious but stable condition.
A memorial to the young woman was erected at the scene of the crash using police cordon tape and flowers.
Police had not released her name at time of going to press, saying they still had other family members to contact.
Mr Rix said it was unclear if drugs and alcohol were involved or speed was a factor.
The serious crash unit is investigating.