CANBERRA mother Tania Klemke was mauled to death by her own dog when she was trying to save a male visitor the animal was attacking.

Klemke, aged in her 40s, was mauled to death in the early hours of this morning by her dog in her own home.

In the wake of the attack, ACT City Services minister Meegan Fitzharris said that the dog, understood to be a mixed breed, had previously bitten someone so badly they required 42 stitches.

"Whether we knew enough at the time to have it declared as a dangerous dog is another matter we're following up on," Fitzharris said.

"Clearly the dog was dangerous, clearly the dog has attacked someone overnight, someone we understand to be their owner or carer and that woman has died," she continued.

Police attended the Watson address after the neighbours heard people screaming for help about 3.30am.

When police arrived and attempted to help the woman, who was lying on the ground inside the home, the dog attacked officers.

"While CPR was being performed on the female victim, the dog made moves towards attacking the police officers. To protect themselves and also preserve the scene, there was a necessity to discharge the firearm," Detective Acting Superintendent Tony Crocker said on Wednesday.

The man remains in hospital, having also been bitten by the dog.

"He doesn't appear to have life-threatening injuries, and is in a stable condition."

"He appears to have received a bite mark to the inside of his leg."