Passersby’s “heroic” actions could have saved the life of a 17-year-old girl who was critically injured in a dog attack in the NSW Hunter Valley region, police say.

Emergency services were called to the girl’s friend’s home on Broughton Street in Singleton, north-west of Newcastle, about 11.30am yesterday.

The girl was attacked by the dog, described as a 10-year-old large mixed-breed, before passersby managed to pull it off her.

Witnesses were first on scene and provided basic first aid until emergency services arrived.

Hunter Valley Acting Superintendent Justin Cornes described the actions of passersby as “heroic”.

“It was an incredible act given the circumstances,” he said.

“They rendered what potentially could be life-saving treatment.

She suffered critical head, neck and body injuries and was flown to John Hunter Hospital.

Police and council rangers were at the scene to euthanise the dog, with consent from the owner, who has been assisting police in the investigation. 

The dog was a mix breed of a boxer, bull Arab, and Irish wolfhound. 

Investigations are continuing, and no charges have been laid.