A 17-year-old girl has died in hospital after being attacked by a dog at a friend's home in Singleton in the Hunter Valley of New South Wales, police said.

Annalyse Blyton was studying at the house last Thursday morning when she suffered serious injuries to her head, neck and body in the incident. She was airlifted to Newcastle’s John Hunter Hospital in critical condition and police were notified on Monday that she had died.

The dog, described in reports as a 10-year-old mixed-breed—variously characterised as a boxer-bull and Irish wolfhound cross—lived at the home. Police said the animal was shot dead by officers at the scene with the consent of the owner. Singleton Council rangers assisted police during the response.

Acting Superintendent Justin Cornes said emergency services and members of the public were confronted with "quite a confronting scene" and praised passers-by who intervened to remove the dog. "Running into a scene which they didn’t have the full circumstances and to jump in there and remove the dog, which was at the time, very aggressive… [it’s] an incredible act," Supt. Cornes told reporters.

New South Wales Police said investigations into the fatal attack are continuing. A report will be prepared for the coroner as part of the inquiry.

Police have not released further details about the circumstances leading up to the attack or whether any enforcement action will be taken against the dog's owner. Authorities typically compile witness statements, medical records and scene examinations as they prepare coroner reports in fatal incidents involving animals.

Dog attacks that result in serious injury or death are relatively rare in Australia but prompt statutory and coronial reviews to assess public safety, animal management and welfare considerations. Local councils and state police often collaborate in such investigations; council rangers can assist with animal control and evidence gathering while police lead criminal and coronial enquiries.

Community members in Singleton expressed shock at the news, while emergency services personnel noted the difficult nature of responding to aggressive animals. The John Hunter Hospital did not comment beyond confirming it had treated a patient who was critically injured following an animal attack.

Police asked anyone with information about the incident or who witnessed the attack to contact NSW Police. Further details will be released as the investigation and the coroner’s processes proceed.