A three-week-old baby girl is in a critical condition after she was the victim of a violent attack this morning.

The Invercargill baby was flown to Starship Children's Hospital in Auckland. Police say she has "life-threatening injuries".

Officers were called to a home in Invercargill at about 5.30am this morning after a call from one of the girl's parents.

Two neighbours said they woke to a "loud piercing bang" before about six police cars arrived at the scene.

Police would not say if either of the girl's parents accompanied her to Starship. They also refused to reveal the type of injury the baby suffered, only that she "was hurt in a violent attack".

However, police said they were not seeking anyone else other than the girls' parent in relation to the incident.

Neighbours said they had not seen children at the property before, but said the couple living there were friendly and approachable.

"I didn't even know they had a baby over there," one neighbour said, adding the couple were quiet and there had been little trouble at the house before.

The house was cordoned off and a security guard at the scene said he expected to be there all day.