Police were investigating the condition of the quad bike, he said. "It wasn't a road-going quad bike, it was a farm-type bike."
They were also still trying to establish how the man came off the quad bike, Mr Scarrow said. He was not wearing a helmet.
"We have spoken to witnesses and we are continuing to speak to more."
Unlawful use of similar vehicles in the area was common, he said.
"Over the years - because it's a beach suburb, we often get reports and see ourselves, trail bikes and other bikes riding in the area to and from the beach and from time-to-time there is excessive speed and no helmets being worn which concerns us greatly."
The man lived in the area, he said. Police were speaking to his family.
Hood St resident Hannah Taylor said she came out of her house when she heard sirens and saw a group of six people around the man.
Four of the men "took off" when they heard the sirens, she said.
"One guy was like, 'nah, he's gone'. That's when they ran off." One of the men drove past the crash site later in the day, Ms Taylor said.
The remaining two men stayed, and Ms Taylor later saw them leave in a police car.
Mr Scarrow said the group of men were believed to have been family members of the man who died.
"I don't think there was anything suspicious in that itself -- it was just a reaction by them at the time."
Another resident said people on quad bikes and scooters were always "hooning up and down the street".
Police are seeking witnesses to the crash. Anyone with information should call Constable John Redley at the Wanganui police station on (06) 349 0600.
