Two young Lower Hutt children have been hospitalised with "very, very severe" injuries believed to have been inflicted deliberately over "a long period of time", police say.
The children, discharged from hospital on Friday, had a "multitude of broken bones" and "lacerated internal organs".
The two children are aged four and five. One had "brain bleeds and severe internal injuries", police said in a statement.
The suspected abuse was uncovered two weeks ago, when one of the children was taken to hospital in an ambulance. Hospital staff alerted police.
"A medical assessment of the child and their sibling revealed further injuries believed to have been sustained in previous incidents," police said on Friday. "Their injuries were so extensive one required surgery, and it has taken weeks to understand the full extent of damage to their bodies."
Police said the children's family had recently moved to Stokes Valley and had been in their new home just two nights when they were hospitalised.
"These injuries do not just happen; it's likely someone knows something or has seen something and that's why we need the community's help."
Detective Senior Sergeant Rebecca Cotton told media on Friday afternoon both children were safe, and police were working with Oranga Tamariki.
The children were known to police and Oranga Tamariki. Police had been to the family's home previously, but there were no concerns for their safety.
Police do not believe adults other than the children's mother were living at the address.
"We don't believe there were other people residing there, but we do believe that there were a number of people frequenting the house, coming and going from the house," Cotton said.
Police did not believe they had been given the full story by those they had spoken to so far.
"The family is cooperating with us to varying degrees," Cotton said. "We do feel that some people that have spoken to police have more information than they've already disclosed, so we're urging those people to come back and tell us everything they know.
"For anybody else in the community that hasn't spoken to police, if you have information about how these children were hurt, please come forward."
The children were interviewed by police on Friday, but Cotton would not say what they had told them.
"I'm really confident that if people out there in the community know this family, they will know who I'm talking about. Look, I think the information we're looking for from people will be quite obvious to the people that have seen the things we're interested in."
Anyone with information was urged to contact police on 105, citing file number 240308/4647, or call Crime Stoppers anonymously on 0800 555 111.
Cotton said police were frustrated with the number of child abuse cases and the difficulty of investigating them.
"I live in Lower Hutt, and like a number of communities and towns around New Zealand, we have issues with child abuse. Police continue to work with our partner agencies and get in there and make children safe, wherever we can. We need people in the community to stand up and speak up for some of the most vulnerable people in the community."
