A major South Australian shopping centre was plunged into lockdown on Sunday afternoon on reports of groups of armed youths fighting in the shopping centre.

Just before 3pm on Sunday, police were called to Westfield Marion Shopping Centre on reports of two groups of young men fighting in the food court area.

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It was reported that some people in the groups were armed with weapons.

As a result, the shopping centre was plunged into lockdown, with digital signage inside telling shoppers to run or hide.

SA Police Assistant Commissioner Scott Duval told reporters that it appeared one group of boys approached and attacked another.

He described both groups as being younger than 18 years old and said the weapons seen in CCTV were akin to expandable batons.

However, he acknowledged some witnesses had reported knives were involved, and that police weren’t discounting that other weapons had been produced.

Witnesses directed police to the David Jones store inside the centre, making it the initial point of focus.

“At this stage, we know the identity of two of the victims,” Duval said.

“We would say from the vision, we know this was not a random attack.”

One witness told 7NEWS he and others in the centre’s cinema were told to “run for your lives”.

Armed police were called to the centre with a fence erected to keep the public out.

“Numerous police resources including STAR Group officers attended the centre to commence a search for the groups involved in the initial disturbance,” a South Australia Police spokesperson said.

“A thorough search of the centre was conducted, including rooftops, however the groups involved were not located.

“Several shoppers who sought refuge in shops were safely escorted from the centre.

“Police are satisfied that there is no ongoing threat to the community.

“Further investigations are being carried out to identify the groups involved.”

Footage from inside the shopping centre’s food court, believed to be taken in the moments before chaos erupted, shows young men with hooded jumpers on running.

Witnesses told 7NEWS they were “petrified”.

“People just started flooding into the cinema, and just sprinting, yelling ‘run, run for your lives, someone’s in here’,” one said.

“We all just started running, people were piling over (each other), and we just ran out the exit.

“We were petrified.”