A stock car driver died after a crash at the Huntly Speedway in Waikato on Saturday night.
Police say he was injured while driving just before 8pm and died shortly afterwards while being treated by ambulance staff.
Inspector Jeff Penno says full details of what happened during the race are still being investigated.
Any spectators who filmed the race are asked to give their footage to police to help the investigation.
The Department of Labour is to take over the investigation.
Speedway New Zealand won't comment on what caused the crash.
Huntly Speedway vice president Nigel Wilton says the crash is a tragic occasion.