Hamilton's boxing community is grieving at the news an amateur fighter died during a bout.
Neville Knight, 49, collapsed during the bout at Te Rapa Racecourse last night and could not be revived.
It was not clear yet what caused his death.
Mr Knight was participating in a series of amateur fights sponsored by the supermarket chain Foodstuffs.
Acting Inspector Andrew Mortimore said officers were called to the scene at around 9.15pm.
Paramedics and a doctor who was already on site conducted CPR on Mr Knight for at least 30 minutes, but he died at the scene, Mr Mortimore said.
Two of Mr Knight's family members participated in last night's boxing, and others were watching the bouts.
Mr Knight was part of a boxing team organised by Nabby's Boxing Gym.
In a statement, the gym said it was devastated by the death, and was supporting Mr Knight's family.
Police said they were speaking with witnesses and were conducting inquiries on behalf of the coroner.
Worksafe had been notified.