The unnamed officer then tried to resuscitate him until paramedics arrived by carrying out CPR, but he could not be revived.

Images on social media show her crouched over the body of the attacker as blood pools around his head, while another clip shows her trying to resuscitate a victim lying motionless inside the shopping centre.

A shopper, who was not named, described the officer’s actions to Australia’s ABC News: “He just started floating towards us and all I heard was ‘put it down’ and then she shot him.

“But we were in no doubt, if she didn’t shoot him, he would have kept going. He was on the rampage.

“Then she walked over and gave him CPR. He had a big blade on him, she chucked the knife away. He looked like he was on a killing spree.”

Australian Prime Minister Anthony Albanese said: “The bravery of the police officer … she entered the proceedings that were taking place, obviously very dangerous, by herself. She is certainly a hero.

“There is no doubt that she saved lives through her action and it is a reminder that those people who wear uniform are people who rush to danger, not away from it, and I give thanks to every one of them for the actions that they have taken up to now and the actions that they will take over the next coming days, which will be a difficult period as well.”

Five of the six victims killed were women, while eight people, including a nine-month-old baby, were taken to hospital with stab wounds, New South Wales Police Commissioner Karen Webb told a press conference.

Reports have suggested a woman who died in hospital was the baby’s mother.

Webb said officers believed they had identified the attacker as a 40-year-old man but were waiting to officially confirm his identity, the BBC reported.

Footage and photos circulated on social media showing the inside of the shopping centre during the attack, including one dramatic clip showing a man on an escalator, brandishing a bollard at the attacker who is holding a large knife.

Other videos showed people running through the shopping centre as an alarm rings and later footage showed police cars lining the road outside.

Ayush Singh, 25, was working in a cafe in the mall when he saw the attack and then heard gunshots as police responded.

“I saw the guy with the knife running and chasing people. As he walked just past beside me I heard two or three gunshots and the guy was neutralised,” he told Reuters.

“People around me were terrified. There were some old ladies I helped to get them inside a safe place inside the cafe.”

There were no indicators that suggested the incident was terror-related, police said at a televised briefing on Saturday evening. They said the offender acted alone.

“I am content that there is no continuing threat,” said Assistant Commissioner Anthony Cooke.

News website news.com.au reported witnesses claiming a man began stabbing shoppers at random.

Hundreds of people were evacuated from the shopping centre, media said. Two witnesses told Reuters they heard shots fired.

“Even 20 minutes after people were rushed out of the mall, I saw SWAT teams of people sweeping the surrounding streets,” one said.

The prime minister described the “devastating scenes” as “beyond words or understanding”.

Additional reporting by dpa, Agence France-Presse, Bloomberg