A milk crate, a chair and a fireman: The "heroes" of the Sydney stabbing.

On Tuesday afternoon, a young man attempted to stab a number of people in Sydney’s central business district. At the time of publication, one woman had been rushed to hospital.

Police are currently investigating whether the death of another woman in a Clarence Street unit is linked to the stabbing. She was found at 3.15pm on Tuesday.

But once the man was seen to be holding a knife just before 3pm, it took only minutes for several members of the public to restrain him, trapping him under a chair and a milk crate until police arrived at the scene.

Witnesses have told AAP that a young man armed with a 30-centimetre kitchen knife began yelling religious statements.

A video belonging to Seven News has emerged of the man, estimated to be in his 20s or 30s, jumping on top of a car, and waving the kitchen knife.

Another man tentatively approached him, armed with a chair.

The young man’s shirt was stained with blood, and he can be heard on the video shouting as he edges backwards.

He was then pursued by a number of men, one a fire fighter holding an axe.

The men shouted at civilians, “Get out of the way” as they attempted to restrain him.

You can watch the full video, here. 

Just outside a cafe, the man was apprehended, as one person placed a chair over his body, and another a milk crate over his head.

When a civilian began reprimanding him, saying, “They are people you just stabbed… I’ll kill you right now,” the group told him to “Stop”.

“We’ll wait for the cops,” another can be heard saying.

Police arrived around 3pm, in response to reports that a woman had been stabbed on the corner of Clarence and King Streets.

It has since been reported that the woman sustained a single stab wound near Hotel CBD, and has been taken to St Vincent’s Hospital in a stable condition, emergency services confirmed.

The woman was photographed at the scene on a stretcher being put in an ambulance by paramedics. She was sitting up and appeared to be conscious.

Her condition was described as “not life-threatening”.

Police have praised the members of the public involved in restraining the man as “heroes”.

A UK man named Lee Cuthbert was among those who helped tackle the stabber, and has since told The Sydney Morning Herald he didn’t think twice about his act of bravery because Australia is his “new home”.

“We had a window open to get some air in and then we just heard the commotion… we looked out and saw him on top of a car wielding a knife and we all just kind of reacted from there,” he told the publication.

More to come.