A pregnant woman is in a critical condition after being allegedly assaulted and run over in Sydney’s south-west this morning in an alleged domestic violence attack.

Three children were at the Narellan Vale home when the woman was allegedly struck in the face with a glass vase, before she tried to leave the property and was allegedly run over by a Mazda sedan.

Police will allege the incident began before 8.30am when the 36-year-old woman and a 36-year-old man, who are believed to be in a relationship, got into a verbal argument inside a car.

The woman is now fighting for life in hospital. (Supplied)

The argument continued inside the Maddison Court home, where the man allegedly broke a television before attacking the woman.

She called police at about 8.30am before running outside to seek aid from neighbours.

It is alleged the man followed her outside, before striking her with the Mazda and running her over.

Police arrived to find her with serious injuries.

She was treated at the scene by paramedics before being airlifted to Liverpool Hospital.

The woman reportedly sustained a broken pelvis, internal injuries, abrasions and lacerations.

The condition of her unborn baby is unknown.

Detective Chief Inspector Paul Albury said responding officers were met with a confronting scene.

“They were met with a pretty horrendous scene,” he said at a press conference.

“The woman had suffered serious injuries, there were three children inside the home, ranging in age from six to 15.”

He clarified the children were unharmed.

Detective Chief Inspector Paul Albury said his precinct responded to a domestic violence call once every two hours. (Nine)

The man is known to police but not for domestic violence offences.

Albury confirmed there was no apprehended violence orde r(AVO) against the man, and that while police had been to the house before, it had not been for a domestic violence incident.

About 11am, a 36-year-old man was arrested in a phone box on Camden Valley Way.

Albury confirmed the car was found abandoned on Wattle Green Place in Narellan Vale, where a crime scene has been established, less than 2km from the home.

He was taken to Narellan Vale Police Station, where he is assisting police, and is expected to be charged this afternoon.

Albury said the incident was a reminder of the prevalence and dangers of domestic violence, claiming his precinct responded to a domestic violence call once every two hours in Camden.

He said neighbours and witnesses were still reeling from the alleged attack.

“A number of witnesses came to the aid of the woman… those people are deeply shocked by what has occurred,” he said.

“It’s a quiet neighbourhood, they are stunned by the level of violence that has been displayed.”

Police are urging anyone with information or dashcam footage from both locations to come forward to Narellan Vale Police Station or to contact Crime Stoppers on 1800 333 000.