There was also evidence to suggest the car may have been racing another vehicle, which did not stay at the scene.
Two male passengers aged 16 and 17 are in critical condition in hospital, the female driver has serious injuries and an 18-year-old female passenger has moderate injuries. The 17-year-old male was flown to hospital by rescue helicopter.
Police are appealing for sightings of the dark blue BMW on Racecourse Rd during the evening.
"We're also keen to speak to anyone who knows anything about the second vehicle that was involved in this. We believe the two cars may have been racing and we want to speak to the occupants of that vehicle urgently," Mr Adamson said.
Anyone who saw the BMW on Racecourse Rd last night or saw two cars racing in the area should contact Waipukurau Police on 06 8589140. Alternatively, information can be left anonymously on Crimestoppers 0800 555 111.