'Can't get boy's face out of my head': Witness retells Sydney carjacking

A bystander who attempted to save two children during a pursuit and carjacking in Sydney's south-west, described the moment a man allegedly lunged at him with a knife.

About 3pm on Saturday, police were called to carry out a welfare check on a 36-year-old man in Lakemba, but he fled in a vehicle with two children.

Police engaged in a short pursuit through the Campsie area, which they said was called off due to the "manner of the man's driving".

The car crashed at the intersection of Parramatta Road and Bombay Street at Lidcombe, about nine kilometres away, where members of the public attempted to intervene after the man got out of the car with the children.

Nicholas Karagiannis was driving along Parramatta Road when he came across the crash scene.

While rendering assistance to the driver, the 46-year-old said he heard bystanders yell, "He's getting away" and "He's got children".

Mr Karagiannis said he chased after the man, who was allegedly attempting to enter other vehicles while armed with a knife. 

Instinctively, Mr Karagiannis said he wanted to make sure the two boys were okay, but "everything happened so fast". 

"He had a knife in his hand, he did not look well," he said. 

"I can't get that boy's face out my head."

Video shows Mr Karagiannis and several other men attempting to subdue the man in the middle of a busy road. 

At one point Mr Karagiannis managed to grab one of the young boys "but the boy wanted to go back".

"They were just crying …in shock, my heart bleeds for those kids," he said. 

Mr Karagiannis said he pleaded with the man to let the children go to no avail.

In the video, the man appeared to bundle the boys into a black Kia Cerato, and moments later the female driver is forcibly thrown from the car. 

Police said the man allegedly threatened the woman with what they described as "a small black knife". 

"I just did what I think anyone else would do in that situation [when] you see a guy with a knife and two young boys," Mr Karagiannis said.  

The children, aged between five and seven, suffered minor injuries and were expected to be released from hospital on Sunday. 

Second altercation

Inspector Mark Wakeham said a member of the public had unsuccessfully tried to remove the keys from the Cerato's ignition, sustaining a laceration to his hand as the man sped off with the two children inside. 

The vehicle came to a stop on the M4 near the overpass of Greystaynes Road before being approached by members of the public, including an off-duty police officer, Inspector Wakeham added.

Bystanders this time managed to restrain the man before police arrived.

Inspector Wakeham described their actions as "incredibly brave".

"They did a wonderful job and we'd like to thank members of the public for assisting us with this case."

He ruled out the incident as an act of kidnapping. 

The man remained under police guard in hospital on Sunday where he was charged with three offences, including aggravated robbery with wounding, police pursuit and reckless wounding. 

In the afternoon he appeared in court from hospital via a video link. 

He did not apply for bail with the matter adjourned until September 24.