He said alcohol was likely to have contributed to the accident, which happened on an unlit stretch of rural road.
The female driver, who was taken to hospital suffering shock after the crash, had been on her way to work and was not speeding.
Detective Haughey said victim support had been called in to help the parties involved, including Buller High School.
Meanwhile, a young woman was also seriously hurt when she was hit by a car in Otahuhu today.
The accident was the third in 24 hours involving a pedestrian being hit by a car, after a 13-year-old girl suffered a possible broken ankle and a dislocated kneecap in a hit and run in Whangarei.
In today's accident, emergency services were called to the scene in Walmsley Rd, Otahuhu, this afternoon.
"The pedestrian is a young woman. She is in a serious condition and has been taken to hospital,'' police said in a statement.
