One person died and four others were injured -- including a child and a pregnant woman -- after two vehicles, each with two occupants, collided head-on in south Waikato about 6 last night.

Police said two people were seriously injured and two had moderate injuries, after the collision on State Highway One, just south of Hydro Road in the Karapiro area.

A south-bound people mover and a northbound sedan collided head-on.

The driver of the sedan remained trapped in the vehicle and died at the scene, while a five-months pregnant woman in her 30s -- a passenger in the people mover -- was flown to Waikato Hospital with a fractured sternum.

Several other passengers, from both vehicles, were transported from the scene by road ambulance.

Two of the four patients have now been discharged from Waikato Hospital, including the child.

The pregnant woman, and a man are both in a stable condition.