Three people have been attacked by two dogs at a house in Sydney's west this afternoon.

Key points: The man had been trying to protect a mother and her daughter

The man had been trying to protect a mother and her daughter He suffered multiple dog bites and is in an induced coma

He suffered multiple dog bites and is in an induced coma Authorities will talk with the owner about euthanasing the dogs

A 40-year-old man was bitten multiple times and went into cardiac arrest at a home on Vincennes Avenue at Tregear.

Police were called to the property about 1:00pm following reports of a dog attack.

The man, who is staying at the house and is not the owner of the American Staffies, was being visited by a 30-year-old woman and her 10-year-old daughter.

It is understood one of the dogs bit the girl on the back and the mother was bitten on the forearm as the pair tried to flee the home.

The woman called the police, however the man remained inside the house where he was mauled by both animals and sustained injuries to his ears, face, abdomen and chest.

The owner then arrived home and locked the dogs in a back room.

Neighbours have described hearing screaming, while paramedics said there was a lot of blood at the scene.

NSW Ambulance inspector Phil Templeman said first responders found "quite a distressing scene".

He praised bystanders and other family members who were left with "blood on them from the victims" after trying to come to their aid.

"Everybody who was on scene at such a horrific and distressing scene should be commended for their efforts to try and bring these animals under control and essentially save the lives of these victims," he said.

One neighbour, who didn't want to be identified, described the scene as chaos.

"There were police and ambulances and it was quite terrifying — we heard some screaming — really awful to know three people were attacked by a dog," he said.

The CareFlight helicopter landed at a nearby park and a specialist doctor and critical care paramedic provided resuscitation and a blood transfusion at the scene.

He was placed in an induced coma before being taken to Westmead hospital in a critical condition.

Dog handlers remove a sedated American Staffy from the home. ( ABC News )

The woman, who is a friend of the man, and her daughter were also treated in hospital.

The RSPCA attended the scene and the dogs were sedated and taken to a vet for examination.

A spokesperson for Blacktown Council said they would then be taken to an animal holding centre.

"Discussions will be held with the owner regarding euthanasing the dogs," the spokesperson said.

If the owner decides to keep them, a mediation process will take place with police and the council, to determine whether the dogs should be put down, he said.

There were 4770 dog attacks reported to local councils in the 12 months to June last year, resulting in 681 people either requiring medical treatment or dying.