Kiwi teen Pono Wairua Aperhama died after swimming pool incident in Australia

A disabled teenager who died at a pool in New South Wales yesterday after suffering a medical episode had been fighting for years to recover from a bike accident, his Northland mum says.

Pono Wairua Aperahama, 17, died at Lambton Pool in Newcastle, where he had been accompanied by his carer.

His medical issues stemmed from being hit by a car while riding a bike years earlier - an accident that put him in intensive care.

His devastated mother said the accident led to his medical problems.

Police were called to the pool at 5pm on Tuesday after receiving reports a boy who had been visiting the facility with his carer had assaulted an employee.

Witnesses reportedly had to hold Pono down until emergency services arrived.

One witness, named Robyn, told the Daily Mail Australia Pono was "distressed" and shouted "You're hurting me" while pinned to the ground

'They put him down on the ground with quite a bit of force. He was still trying to lift his head up, he kept shaking his head and hitting it on the ground,' she said.

By the time paramedics arrived Pono was in a serious condition. He was treated at the scene and then taken to John Hunter Hospital, where he died.

Lambton Pool was closed after the incident. News Corp Australia / Peter Lorimer

Pono's mother Te Rina Abraham of Whangarei said she was organising to fly from New Zealand to Sydney. It had not been decided where Pono's final resting place would be.

Abraham said Pono's brain injury from the bike accident led to his medical problems.

Now, after fighting to recover for years, he had lost his life.

"Health issues were caused by his accident. He was perfectly healthy otherwise. He was born the smallest of my six babies and the easiest. Not much pain at all he slid out ... I could have had 10 of him if I knew birth was that easy," she said.

"My heart has been pulled out of my body and thrown into pieces on the ground ... I am speechless.

"I also had to fly from New Zealand to Australia when he had his accident.

"My king was the love of my life and my everything. He made me the person I am today.

"The fight he endured just to live. He made me realise anything in life is possible if you want it so much."

Pono Wairua Aperahama developed medical issues after being hit by a car while riding his bike. Photo / Facebook

A heartbroken friend this afternoon said that Pono was a "cheeky" fella who was "always smiling".

"He was a fighter. His tough spirit got him through a lot. He never gave up and always had a smile on his face," the friend told The Daily Telegraph.

The friend confirmed he had been in a bike accident years earlier which put him into intensive care at The Children's Hospital at Westmead.

"He was riding a bike when a car hit him," they said.

"It was horrible. He was (in ICU) for quite some time."

Newcastle Assistant Commissioner Max Mitchell said the incident was tragic and the boy was self-harming after suffering a medical episode.

He had a pre-existing condition and had been at the pool with a carer.

Assistant Commissioner Mitchell said there were reports the teenager was punching himself to the head and even smashing himself into the concrete.

"What is alleged to have occurred is the male was punching himself to the head area," he said.

Newcastle Police launched a critical incident investigation following Pono's death. Photo / Daniel Irwin

Family and friends, many of whom are based in New Zealand, have paid tribute to Pono this afternoon on social media and sent condolences to his whanau.

One friend wrote: "You'll always be remembered bro. Not for what happened but for who you are as a person and friend. I wish we got to have that catch up we spoke about."

Another said: "Rest easy my brother. I will always remember you."

One neighbour, Susan Clark, who witnessed the incident told The Daily Telegraph she saw eight people trying to restrain Pono from her home.

"It is disgusting to have that pool open eight hours after a 17-year-old was killed," she said.

"Eight people were holding down a 17-year-old. It was traumatic.

"We saw a paramedic on top trying to bring this child back to life.

"What happened that it got to that point where the child got into cardiac arrest?

"I feel for the family."