The family of Neville Knight were watching his boxing bout when he collapsed against the ropes and died in the ring at a charity fight night in Hamilton on Saturday.
Knight's fiancée, Michelle Burke, tried to save his life by administering CPR, event organiser Dion McNabney told Fairfax Media. The couple, who were both passionate about boxing, were due to get married next month.
McNabney said it wasn't a punch that caused Knight to collapse, but that his death appeared to be a freak medical event.
"He just dropped in the second round," McNabney told Fairfax.
"I knew something wasn't right, so I run around the side of the ring."
"The doctor and the corner man just put him in the recovery position and just took his mouth guard out.
It looked like he was having a seizure. I just screamed out 'Call an ambulance'."
Knight's 10-year-old stepson had fought in the event earlier in the night and was also in the audience.
Medical staff and his fiancee worked for over 30 minutes to try and resuscitate Knight, but "he was gone," McNabney said. A memorial would be organised at the gym for the dead fighter.
Tributes have been flowing in for Knight on Facebook today, with friends and family honouring him as "a great mentor for our young people", a "well respected man" and someone who was always up for a laugh.
The charity boxing event was run by Nabby's Boxing Gym, which is owned by McNabney, and a post on the gym's Facebook site earlier this morning said Knight was nicknamed the 'Terminator.'
Three of Knight's family members had fought in the event before his death and they "loved the sport," the post said.
Police have referred Knight's death to the coroner.
Knight was listed to fight Nick Trott, a former DJ for The Rock, who told Fairfax Media last night he was "numbed" after the incident.
"I'd like to send my prayers to Nev's family. I know them, I trained with Mitch, his fiancée. I weighed in with Nev this morning. We both did our medicals. It's numbing," said Trott, who fought fellow radio host Grant Kereama in the 2003 Fight for Life.
Hamilton boxing coach Merrill Purcell said Knight was a good fighter and had fought two of his boxers in the past few years, including the Tongan Bear last year.
"I knew Neville. He was one of the nicest guys around... He could handle himself. He was pretty good. He wasn't sickly or didn't seem to have any medical problems. He was good."
Purcell, who was attending another fight in Hamilton last night, said the news had come as a shock.
"He's a corporate boxer. A corporate boxer is one that hardly fought. Generally a corporate boxer is one that trains for six weeks/two months. They usually just have one fight and that's all."
Purcell had seen him fight three times and recalled training Knight's son at the Nawton Boxing Club last year. "He was a very strong man Nev. It's kind of a surprise.
"I think he went there (Nabby's Gym) for the exercise and because he was so popular he got in the ring. Everyone he was around was a fighter - I had most of his workers at my gym."
Purcell said it was compulsory for boxers to provide medical certificates from their own doctors and also have a medical from a doctor before a fight weigh-in. He said it was not uncommon for people to get hurt, but he couldn't recall anyone dying in the ring.
Last night's event was dubbed "Young Guns 2".
It appears many of the fighters were inexperienced. In the run-up to the event, the Facebook page for Nabby's Boxing Gym complemented the skills of a boxer with only three prior bouts under his belt.
Just hours before the event, another post encouraged all participants to enjoy their charity fights, saying "Only hours away until kickoff big ups to everyone from our Foodies Fight Night crew that has been training for the last 10 weeks it has been amazing to see how far you guys have come, win or lose you have done yourself proud and myself Ike and Scotty. Get out there and enjoy yourself tonight [sic]."