Two babies are in Waikato Hospital being treated for non-accidental injuries.

A 15-month-old boy and an 8-month-old girl were admitted yesterday.

DHB Communications Director Mary Anne Gill said they were both in a stable condition in a ward.

A third baby - a six-month-old girl - was also admitted to Waikato Hospital yesterday with serious head injuries, but has since been transferred to Auckland's Starship Hospital.

Earlier today Waikato police said they were investigating how the six-month-old suffered the head injuries.

The baby girl arrived by ambulance at Waikato Hospital about 4.40pm yesterday and was admitted to the intensive care unit.

Police have secured a Ngaruawahia house and investigators have begun an enquiry.

Police and Child Youth and Family Services are still gaining an understanding of the circumstances and family members are assisting in that process, police said.

- NZ Herald online