A six-year-old girl from the Hutt Valley died when the quad bike she was riding fell on her after she hit a fence.
She was attending the Jayden Kilmister memorial ride when the accident happened about 2pm on Sunday.
Police said she could not be revived and died at the scene.
The serious crash unit investigated the accident and the death has been referred to the coroner.
The event was to honour avid trail-bike rider, Jayden Kilmister, who died in 2009 when he was blown off a ute on a farm.
An early report said the girl was riding a trail bike.