A coroner's report reveals the occupants of one car were seen huffing nitrous oxide before crashing in May 2024 - killing five people

Open Justice reports 19-year-old Piata Otufangavalu was driving unlicensed with two occupants on State Highway 3 just north of Te Awamutu.

There were no survivors when their car ploughed into that of Hamilton couple Paul and Lois Grimmer.

In the coroner's findings released today, one witness recalls seeing Otufangavalu and a passenger with "big green balloons" and thought they were "huffing nangs".

Coroner Matthew Bates says the driver also had cannabis in her system - which may have exacerbated her impairment.