A 32-year-old man has been arrested after an eight-month-old baby was assaulted in Hamilton on Sunday morning.
Police say the baby, who was rushed to Waikato Hospital with critical injuries, has been transferred to Auckland's Starship Hospital for more specialist care.
The emergency services were called to the address in Hamilton East just after 11.30am.
Acting Detective Inspector Mark Greene said a man from that address was helping them with their enquiries and has now been arrested and charged with assault.
The man will appear in the Hamilton District Court on Monday.
The house where the baby was found remains under police cordon on Sunday night and will be examined by forensic experts on Monday.
Mr Greene said while an arrest had been made the investigation was still in its early stages. He said the only thing he can confirm is that the incident involved domestic violence and he urges those affected by it to ask for help.