The man who fatally stabbed six people in a horror attack at a Sydney shopping centre has been identified as 40-year-old Joel Cauchi who moved to Sydney from Queensland last month.

NSW Police Assistant Commissioner Anthony Cooke said the man was known to authorities in his home state.

“We are and have spoken with his family and we will continue to do so and they are co-operating with us,” he told reporters on Sunday.

“We have received no evidence that we have recovered, no intelligence that we have gathered that would suggest that this was driven by any particular motivation, ideology or otherwise.

“We know that the offender in the matter suffered from mental health.”

Cauchi was shot dead by a lone female police inspector at the scene after he lunged at her with a large knife. People fleeing the scene had directed her to where the attacker was.

The mass stabbing on Saturday afternoon at the Westfield centre at Bondi Junction has prompted a massive police investigation.

Six people, five women and one man, were killed in the attack and several others were injured.

Four female victims aged between 20 and 55 and a man, aged in his 30s, died at the scene.

A fifth female victim, aged 38, died at St Vincent’s hospital on Saturday night.

One of those killed has been named by multiple media outlets as Dawn Singleton, the 25-year-old daughter of multi-millionaire businessman John Singleton.

Two of the six victims were from overseas and have no family in Australia, Mr Cooke said.

The number of people in hospital rose by three overnight, taking the total to 12.

A nine-month-old baby was among those stabbed and underwent surgery on Saturday night, NSW Police Commissioner Karen Webb told reporters on Saturday.

NSW Health Minister Ryan Park said on Sunday the child remained in a critical condition in ICU at the Children’s Hospital in Randwick.

The child’s mother was one of those who died, passing her baby on to strangers and begging them to help before she lost consciousness, Sydney’s Daily Telegraph reported witnesses as saying.

Prime Minister Anthony Albanese said the senior female police officer who shot the assailant was “certainly a hero” who no doubt saved lives.

The shopping centre is closed and will be an active crime scene for days.

NSW Premier Chris Minns said it was a truly shocking day in the state’s history.

“I can understand that people will be grieving and very angry for the next few days,” Mr Minns told Sydney radio 2GB on Saturday from Japan’s Tokyo Airport, where he was waiting for a flight home.

“It’s literally everyone’s worst nightmare… a wicked and a violent crime,” he said.

Mr Albanese on Sunday morning praised the officer involved along with others who came to the assistance of injured Sydneysiders.

“The wonderful inspector who ran into danger by herself and removed the threat that was there to others, without thinking about the risks to herself,” he told reporters.

“We also see the footage of ordinary Australians putting themselves in harm’s way in order to help their fellow citizens.

“That bravery was quite extraordinary that we saw yesterday.”

Federal Opposition leader Peter Dutton said there was heroism amongst the horror.

“We thank everyday Australians who helped each other get to safety and those who provided comfort to others in distress,” he said on social media.

King Charles said in a statement overnight that he and Queen Camilla were “utterly shocked and horrified to hear of the tragic stabbing incident in Bondi”.

The royal couple praised the “bravery of the first responders and emergency services”.

Pope Francis also expressed his sadness at the “senseless tragedy” and offered his “spiritual closeness” to all those affected.

Emergency service crews rushed to Bondi Junction on reports of multiple stabbings. (Steven Saphore/AAP PHOTOS)

Ms Webb said the inspector was doing well under the circumstances and will be interviewed on Sunday.

“She showed enormous courage and bravery,” Ms Webb said, adding other responding police, civilians and staff at the centre had too.

“It was an awful situation… but it could have been much worse,” she said.

International leaders react to mass stabbing