The scene of a stabbing attack in Sydney today. Photo: Screenshot / ABC
Police have confirmed four people have been stabbed and two are injured after an incident at Engadine in Sydney's south.
A man was travelling in a car southbound on Princes Highway and stabbed his passenger, a woman in her 40s, before crashing into another car, police allege.
Superintendent Donald Faulds, from the Sutherland Shire Police Area Command, said the pair were in a domestic relationship.
"We believe the female was being assaulted in the car while the male was driving the vehicle at the same time," he said.
"A number of witnesses mentioned that the car was driving quite erratically at the time, and we believe that was when the assault was occurring ... and as a result they then collided with another vehicle."
The woman is in a critical condition and another woman who was also allegedly stabbed is in a serious but stable condition.
The man, who police allege got out of the car wielding a box cutter, suffered self inflicted stab wounds and was transported to Liverpool hospital in a critical condition.
The police officer who suffered a laceration to his arm is in a serious but stable condition.
Police respond to the scene in Sydney. Photo: Screenshot / ABC
Police said multiple calls were made to triple-0 after a two-car crash at the intersection of Princes Highway and Old Bush Road about 9am.
A number of people stopped to assist believing it was a normal car accident.
Terrified witnesses have described a man in a bloodstained shirt banging on their car windows.
One witness who did not want to be identified told the ABC he saw the man get out of the car yelling "I'm going to kill you".
"When the cops came he ran down the street screaming. They shot the taser at him right on the footpath here but it didn't even seem to touch the sides, he just kept bolting," he said.
"He was off his rocker."
Officers arrived and found a man who appeared to have been stabbed allegedly running from the scene.
Police used a taser while arresting the man.
A male police officer suffered a wound to his left wrist during the arrest, police said.
A woman, who police believe was a passenger in one of the vehicles involved in the crash, was found suffering multiple injuries.
The ABC understands she was also stabbed.
Mobile phone footage obtained by the ABC shows the man running from the scene with police in pursuit.
In another video he is pinned to the ground under arrest.
One woman told the ABC her boyfriend had rushed to the scene of the crash with a first aid kit and been threatened by the man.
NSW Police Minister Yasmin Catley said an investigation was underway.
"There is no threat to the community, I just want the community to know that there is no threat whatsoever," she said.
A fourth person was also injured. Ambulance crews are also at the scene.
The Princes Highway is closed in both directions near Old Bush Road.
- ABC