By Peter Bodkin in Sydney

A first-time mother defending her baby from a knife-wielding man, the daughter of a millionaire advertising guru and an on-duty security guard are among six people killed in a terrifying attack at a major Sydney shopping centre.

Osteopath Ashlee Good, 38, died after Joel Cauchi, 40, attacked dozens of people – seemingly at random – at Westfield Bondi Junction on Saturday afternoon.

She was rushed to nearby St Vincent’s Hospital in a critical condition but died that night.

Her nine-month-old daughter was also injured during the mass stabbing and remained in intensive care on Sunday after undergoing emergency surgery.

Dr Good, the daughter of former North Melbourne AFL player and board member Kerry Good, was remembered by her family as a “beautiful mother, daughter, sister, partner, friend” and an “all-round outstanding human”.

Two brothers, who did not give their names, told Nine News they helped stem the bleeding from the mother and child’s wounds after the woman thrust the baby into their arms begging for help.

Dr Good’s family thanked the duo after they “held and cared for” the baby when she was unable to do so herself due to her injuries.

“We are struggling to come to terms with what has occurred,” they said in a statement.

South Australian Premier Peter Malinauskas, who went to school with Dr Good’s partner Daniel Flanagan, said it was “incomprehensible” that such a beautiful family had been so “aggressively affected” by the tragic events.

Also among those killed was Dawn Singleton, the daughter of multi-millionaire advertising entrepreneur John Singleton and lawyer Julie Martin.

The 25-year-old, who posted her fiance’s proposal on social media in July, worked for Sydney-based fashion label White Fox Boutique.

She was described as a “sweet, kind-hearted person who had her whole life ahead of her” in a statement from the company.

Another victim was named in multiple media reports as architect Jade Young, who worked nearby in Double Bay.

Two of the six people who died in the attack were from overseas and had no family in Australia, police said.

The victims included five women and a 30-year-old man, a shopping centre security guard who the Ahmadiyya Muslim Community of Australia has named as Faraz Tahir.

The group, who is staging a vigil on Sunday evening, said Mr Tahir had sought refuge in Australia just a year ago after fleeing persecution in his home country of Pakistan.

“He quickly became an integral part of our community, known for his unwavering dedication and kindness.

“Faraz was not only a valued member of the Ahmadiyya Muslim Community of Australia but also actively contributed to the charitable endeavours of the Ahmadiyya Muslim Youth organisation.”

At least 12 others – including nine women – were hospitalised after suffering stab wounds in the attack, although some had been discharged by Sunday afternoon.

NSW Police Commissioner Karen Webb said part of the investigation would involve looking at the possibility Cauchi was deliberately targeting women in his attack, she said.

The 40-year-old, who had recently moved to Sydney from Queensland, had a history of mental health issues and had previously come to the attention of police in both NSW and his home state.

His rampage ended when he was shot and killed by a police officer.

Premier Chris Minns said all of NSW would need to get behind the families of those affected by the tragedy as they went through “the inevitable grief associated with such a horrifying, horrifying event”.

‘Instinctive bravery’: shoppers praised in Bondi attack