The man who fatally stabbed six people at a mall in Sydney's beachside suburb of Bondi seems to have targeted women, police said, as the attacker's father opened up about his son's long history of mental illness and frustrations with women.

Clad in shorts and an Australian national rugby league jersey, Joel Cauchi, 40, roamed through the busy Westfield Bondi Junction on Saturday with a large knife. Five of the six people he killed were women as were the majority of the 12 injured.

He was shot to death by Inspector Amy Scott, who confronted him alone on the fifth floor after a pursuit through the mall.

The attacker's father, Andrew Cauchi, told reporters on Monday he was devastated by the news and said his son had a long history of mental illness and frustrations with women.

"He wanted a girlfriend and he has no social skills and he was frustrated out of his brain," he said in comments reported by The Australian newspaper.

Andrew Cauchi said he had taken five U.S. army knives from Joel when Joel visited him last year as he feared he could get stabbed.

The comments came hours after senior police officers said they were investigating the possibility the attacker had focused on women.

"It's obvious to me, it's obvious to detectives that seems to be an area of interest that the offender had focused on women and avoided the men," New South Wales state Police Commissioner Karen Webb told the Australian Broadcasting Corp.

"The videos speak for themselves, don't they? That's certainly a line for inquiry for us."

Police have said there was no indication ideology was a motive.

The only man killed during the attack was 30-year-old security guard, Faraz Tahir, who had arrived in Australia last year as a refugee from Pakistan, according to the Ahmadiyya Muslim Community of Australia, to which he belonged.

Authorities on Monday identified the sixth victim as Chinese national Yixuan Cheng who was studying in the country.

The New South Wales government announced on Monday a A$18 million ($12 million) independent coronial inquest into the attack but Premier Chris Minns ruled out new rules that would allow private security guards to carry firearms.

Day of mourning

Thousands of flowers and wreaths lay in a makeshift memorial outside the mall on Monday as hundreds came from across the city to honour those killed.

"It's shocking something like this could happen so close to home," said Wren Wyatt, who paid respects at the memorial.

"I'm still trying to get back to everyday life. I've taken today off to try and get my head better," she added.

Wyatt said she was walking past the mall on Saturday when a crowd rushed past her screaming and security told her to flee.

David Spencer travelled more than 50 kms (31 miles) from the city's west with his two young sons to lay a wreath as a family after watching his eldest react with terror to the news.

Mass killings are rare in the country of about 27 million people, which has some of the world's toughest gun and knife laws.

The Australian national flag is flying at half-mast across the country, including at the Parliament House and Sydney's Harbour Bridge, in honour of the victims. Sydney Opera House's sails will be lit with a black ribbon on Monday evening.