Three people have been taken to hospital after a car collided with a crowd on a country road near the Manawatu settlement of Tangimoana.
One of those, a 19-year-old woman was critically injured at what police believe was a gathering of boy-racers.
Emergency services were called to Rosina Road on the outskirts of Tangimoana about 12.30am on Saturday.
Police say a person is now helping them with their inquiries. They say alcohol and speed did not contribute to the incident.
Police say a number of residents had called them earlier in the night to complain about noise generated by several vehicles in the area.
Manawatu District Mayor Ian McKelvie lives on Rosina Road and says the car noise from drag races has become more noticeable in the last few weeks.
Mr McKelvie says racers have painted signs indicating a drag strip on a straight stretch of the road and boy-racer gatherings have become an increasing problem.