A 4-month-old boy is in a critical condition in Starship Hospital after suffering head injuries at his South Auckland home.
The baby was rushed to hospital on Saturday night before undergoing surgery on Sunday for what police believe are "non-accidental" head injuries received at his Papakura home.
The Housing NZ home was yesterday cordoned off while police began investigations into what is suspected to be a case of serious child abuse.
Detective Sergeant Ian McGill, of the Counties-Manukau Child Abuse Team, said the boy last night remained in a critical condition and on life support following the surgery.
His family - including his 18-year-old mother and 19-year-old father - were with him but Child Youth and Family had been called in.
The family was believed to be co-operating with police.
Mr McGill said an ambulance was called to the Papakura home about 9.30pm on Saturday after the baby suffered some head trauma.
He was initially taken to Middlemore Hospital but later transferred to Starship where he had the surgery and now remains under close monitoring.
Neighbours yesterday knew little about the family who lived at the run-down home.
One woman said parties were always being held there and people came and went at all hours.
Another woman said police had arrived at the house about six months ago.
Moments after they arrived, all the people in the house came out with their hands above their heads.
She believed it was in relation to drug dealing at the house.
Yesterday, an alcohol box and several empty beer bottles lay on the unmowed lawn, alongside other bits of rubbish.
The front window was smashed and shards of glass lay on the ground.
A child's stroller could be seen behind a net curtain next to the broken window.
Children's Commissioner Dr Cindy Kiro said she was shocked and saddened to hear another child had been injured.
"It's terrible. Can you just imagine what these kids go through? Often it's not the first time. There's often a whole lot of precipitating things that lead up to the last incident where the child or baby is being abused," she said.
Dr Kiro is due to present a package of actions to tackle child abuse to a family violence taskforce this week.
New Zealand has the third highest rate of infanticide of all the countries in the Organisation for Economic Co-operation and Development.