Police said the man was taken into police custody today in relation to the girl's death at a house in Favona Rd.
He will appear in Maukau District Court tomorrow morning facing a charge of unlawful possession of a pistol.
Under the Firearms Act, sawn-off shotguns are classed as pistols.
At a press conference earlier today, Detective Inspector Faa Va'aelua confirmed the weapon involved was a shotgun.
He said further charges will be considered at the conclusion of the investigation.
Police would not release the girl's name, or the identity of the man charged, because the girl's extended family were yet to be notified. Her name would be released tomorrow afternoon.
Mr Va'aelua said the police investigation was in its early stages. Police were still trying to establish whether or not the death was accidental.
"This is a terrible tragedy for the child's family and our thoughts are with them at this difficult time."
Family members wept and sang as the little girl's body was removed in a hearse.
Sione Tatafu grew up with the father of the 2-year-old girl, and said she was a tomboy.
"She was a smart little girl who loves to come kick it with the boys," he said.
"She was daddy's little girl."
Mr Tatafu, who grew up in Onehunga with the girl's father, said the family was moving house today.
He said both sides of the family were upset and shocked.
"They're just trying to keep it together at the moment."
Police are at a property in Favona Rd. Officers are knocking on doors and speaking with residents on the footpath.
A woman who lived nearby said a mother lived at the house with her partner.
She was a mother of four children: a 7-year-old girl, a 5-year-old boy, a girl 'aged about 3' and a baby born at the end of last year.
More than a dozen police cars line the busy main road and a large cordon is in place.
A resident on the street said she heard a "loud explosion" and then sounds of someone sobbing.
"I heard a very loud bang and then some people were getting on the next-door berm. Someone was crying really loudly. It was very sad sobbing," she told the Herald.
The woman, who did not want to be named, said she and several neighbours had come out of their houses following the noises.
"I've never heard that sort of noise before -- it was so very loud.
"There was someone sitting on the steps there with another child. And there was that sobbing, that really loud sobbing."
The woman said they did not know the family who lived at the property.
"When we go past, there's always toys and things out the front, so I presume they had children."
At the scene, police officers can be seen knocking on doors and speaking with residents on the footpath.
More than a dozen police cars line the busy main road and a large cordon has been put up.
A third witness said she heard a loud bang, followed by people crying.
"I've never heard a shotgun before, but it was one of those really loud bangs, like a car backfiring."
Hysterical screaming can be heard coming from the property.
Members of the public - possibly family - are being allowed into the cordoned off area.
