Hundreds of people are expected to gather at Westfield Bondi Junction in the eastern suburbs to pay their respects to those affected by Saturday's attack, with black ribbons to be displayed inside the centre.

The environment of sombre reflection will be complemented with mental health support and condolence books at the scene.

Wentworth MP Allegra Spender said people had been left devastated by the attack in a shopping centre that served as a community hub.

"Anybody knows it could have been any of us," she told ABC TV on Thursday.

"The word I hear most often is 'senseless' and people are shocked and traumatised."

Scentre Group, which owns and operates the shopping centre, said there would be no retail trade but shops would open for business on Friday with an increased police and security presence.

"The centre will be quiet - it will allow for reflection to occur," chief executive Elliott Rusanow said.

The number of security guards across all Westfield centres will be increased in response to the attack.

The shopping centre will resume normal trading hours on Friday, although Mr Rusanow said some businesses would remain shut.

"It will be their (retailers') choice when they want to re-open," he said.

The re-opening will mark almost a week since six people were killed when 40-year-old Joel Cauchi went on a stabbing spree.

The Queensland man, whose family said lived with mental illness for decades, was shot dead by a police inspector on level five of the complex.

Six people remained in hospitals across Sydney, with one woman in intensive care in a serious but stable condition, NSW Health said on Wednesday.

A nine-month-old baby, whose mother was among five women killed in the attack, was in hospital in a serious but stable condition.

A permanent memorial is being planned near the site, and a beachside candlelight vigil will also be held on Sunday.

Premier Chris Minns said the devastating attack had touched people across NSW, regardless of whether or not they knew the victims.

"This vigil will be an opportunity for the community to stand together to support and honour the victims and survivors of this horrific tragedy," he said.

"I hope they can draw some strength from the fact that there's many people that are standing with them during this time."

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Australian Associated Press