(Photo : Lisa Maree Williams/Getty Images)
Police enter Sydney shopping mall amid deadly knife attack.

Australia's prime minister on Saturday hailed the "hero" police officer who stopped a vicious knife attack at a Sydney shopping mall that claimed at least six lives.

"She is certainly a hero. There is no doubt that she saved lives through her action," said Prime Minister Anthony Albanese, who called the murderous attack a "horrific act of violence indiscriminately targeting innocent people going about an ordinary Saturday."

New South Wales Police Commissioner Anthony Cooke also praised the officer at the same press conference who "took action, saving a range of people's lives."

He said the officer pursued the attacker, then fatally shot him when he turned to confront her.

Albanese did not immediately identify the officer, nor did he or the police commissioner discuss a possible motive for the attacker. Albanese said speculation at this point would be "unhelpful."

The unnamed attacker entered the Westfield Bondi Junction mall late afternoon and began slashing at people. Those not killed were seriously or critically injured, said police. A baby was among those slashed.

The Australian Federal Police and Australian Security Intelligence Organization are continuing to investigate.