Nelson police are investigating whether a fatal road crash on Sunday happened as three cars were racing each other on a country road.
The 21-year-old driver of one of the cars died when his vehicle rolled on a bend approaching the Upper Moutere village outside Nelson.
Emergency crews on the scene say the car was so badly damaged it was difficult to identify the make and model.
The passenger, a 19 year-old man, is in Nelson Hospital with serious head injuries.
Police were on Monday interviewing the drivers of the two other cars.