Six people have been killed in a knife attack at Westfield Bondi Junction shopping centre in Sydney's east.
The offender, who NSW Police believe to be a 40-year-old man, was shot dead at the scene by a senior officer.
Five of the victims — four women and a man — died at the busy centre on Saturday afternoon and another woman died from her injuries in hospital.
Eight others who were injured, including a nine-month-old child, remain in hospital and some are in a critical condition.
As the attack unfolded, some shoppers ran to find safety in stores while others fled the building and some confronted the armed man.
Warning: Some readers may find the following details of the attack, witness accounts and footage of the incident distressing.
NSW Police Assistant Commissioner Anthony Cooke said authorities believed the man acted alone and there was no ongoing threat.
Police Commissioner Karen Webb said police believed they knew who the man was but he had not been formally identified.
She said the man was known to police and, while the motive was unclear, early indications suggested the attack was not related to terrorism.
"There's no suggestions anyone was targeted but that could change," she said.
Police said the man was in the shopping centre at about 3pm before leaving and then returning around 20 minutes later with a knife.
A police inspector, who was nearby, was directed towards the man by witnesses, and she shot him dead after the offender confronted her.
"She confronted the offender, who had moved by this stage to level five, as she continued to walk quickly behind him to catch up with him. He turned to face her, raised a knife," Assistant Commissioner Cooke said.
"She discharged a firearm and that person is now deceased."
Commissioner Webb said the officer was "doing well under the circumstances".
"She showed enormous courage and bravery … we just talked [and] she's OK, her family is OK. She's got everything she needs for the time being."
She said the officer would be formally interviewed on Sunday.
A NSW Ambulance spokesperson said the injured people were taken to a number of hospitals across Sydney.
The baby has undergone surgery at Sydney Children's Hospital at Randwick. Another victim was taken to St George Hospital and another to Royal North Shore Hospital.
Three people were taken to St Vincent's Hospital at Darlinghurst. Another two are at Royal Prince Alfred in Camperdown.
[Map: Westfield Bondi Junction]
Acting NSW Premier Penny Sharpe said the event was horrific and distressing for the whole state, particularly as it came at a time when people were doing ordinary things and enjoying the first day of the school holiday.
"I'm personally distressed by this … This is not who we are, this is not the community that we live in," Ms Sharpe said.
"We hold in our hearts the families and the friends and those who have lost loved ones.
"We stand with those who are waiting to hear from those that have been injured."
She thanked the innocent bystanders who risked their lives to help others, particularly the police officer who stopped the offender.
Premier Chris Minns is in Tokyo on leave, but Ms Sharpe said he had been briefed and was part of a crisis cabinet meeting which would be looking at providing support to those affected.
"This is going to be difficult, it's going to be hard for days to come," she said.
"This is really just the beginning of the pain and the grief for so many people."
Federal police join response to attack
The shopping centre, where a crime scene has been established, will remain closed on Sunday.
A large number of emergency vehicles and personnel arrived at the scene, one of the biggest shopping precincts in the city, after receiving triple-0 calls.
Armed police could also be seen conducting a search of the rooftop car park.
Commissioner Reece Kershaw said the Australian Federal Police (AFP) would support NSW Police in the investigation of the attack.
"The AFP has deployed AFP members to the crime scene and we've offered our full specialist capabilities such as digital forensics," he said.
"It is too early to determine a motive and it would be unhelpful to speculate."
Commissioner Kershaw said he had also spoken to the NSW police commissioner and the director-general of ASIO.
"I want to thank NSW Police, emergency services and first responders and the community for their bravery in the face of this shocking incident," he said.
Prime Minister Anthony Albanese said the attack was "beyond words or understanding".
"Australians will be shocked this evening," Mr Albanese said.
"This was a horrific act of violence, indiscriminately targeted at innocent people going about an ordinary Saturday doing their shopping."
The prime minister praised the bravery of the police officer who confronted and shot the offender.
"She is certainly a hero," he said.
Witnesses describe 'horrific experience'
As the attack unfolded and police responded, shoppers were evacuated from the centre.
ABC sound engineer Roi Huberman said he was inside a shop when he heard gunshots.
"And suddenly we heard a shot or maybe two shots and we didn't know what to do," he said.
"Then the very capable person in the store took us to the back where it can be locked.
"She then locked the store and then she let us through the back and now we are out."
Shopper Adriana was with her two daughters at a beauty store when they heard gunshots.
"All of a sudden the front doors were closed, and in a matter of seconds we heard some gunshots and got sent to the storage room at the back of the shop. There were about 30 or 40 people there," she said.
"Everyone was screaming, crying, trying to call their relatives. It was a horrific experience.
"There was a lot of screaming and people just screaming, 'Get out, get out, get out of the shopping centre.'"
Nearby salon owner Leanne Devine said she was alerted to the attack by "hundreds and hundreds of people" running out of the centre.
"It was absolutely horrific," she said.
"We're in shock mode. We're traumatised."
