An altercation between two groups of teenagers in a food court sent a major Adelaide shopping centre into lockdown.
The incident unfolded at Westfield Marion Centre in Adelaide just before 3pm on Sunday and triggered widespread reports of an armed person inside.
Assistant Commissioner Scott Duval said South Australia Police had reports of two groups of teenage boys fighting in the food court, including some armed with expandable batons.
"(One group) approached another group of boys and an altercation occurred," he told reporters at the scene on Sunday.
"The expandable batons are seen and at this stage, we cannot discount any other weapons but we have reports that a knife may be involved."
Mr Duval said three boys chased the other teenagers through the centre and entered the David Jones store.
"That was the first part of our focus of where we put our specialist attention, to start clearing the centre to ensure the safety of all people could be assured," he said.
"We are at the point now where we are able to clear the centre safely with specialist police and allow people that were still sheltered in place to leave."
The teenagers involved in the incident have yet to be located after a thorough search of the shopping centre but police said they were "confident" the groups would be tracked down.
There is no ongoing threat to the community, according to police.
"I would say that's it's clear from the vision this is not a random attack," Mr Duval said.
"The boys would appear to be known to each other, but obviously we're still in the early days of investigation of the incident."
A 77-year-old woman suffered a shoulder injury while fleeing the centre and another person in their 30s suffered a knee injury, South Australia Ambulance Service said.
One of the patients was being transferred to the Flinders Medical Centre for treatment and paramedics remained at the shopping centre, a spokesman said.
A young woman, who was in the cinema when the commotion began, told ABC News how it unfolded.
"We were in the movies and we just heard this noise going on saying 'emergency'... and nobody really knew what it was - if it was a phone or something," she said.
"Someone went out of the movies and all of a sudden everyone just came running in - just sprinting incoming, yelling 'run, run'.
"Then we got up and started sprinting towards the emergency exit."
Photos of large digital signs inside the centre warned members of the public of an armed offender in the complex.
Social media footage from shoppers showed armed officers storming into the centre while dozens of people attempted to run to safety.
The lockdown comes less than three months after a man attacked shoppers with a knife at a Westfield mall in Bondi Junction, Sydney, killing six people including a security guard.
Westfield Marion is the largest mall in Adelaide and is located in Oaklands Park, south of the CBD.
