Machete threat sparked Westfield lockdown, court told

A machete and extendable batons were allegedly brandished during the robbery of a teen that sparked a lockdown and evacuation at Adelaide's biggest suburban shopping mall.

The incident unfolded at Westfield Marion in Adelaide's south just before 3pm on Sunday, triggering widespread reports of an armed person inside.

Two boys, aged 15 and 16, both from Mitchell Park, appeared in the Adelaide Youth Court via video link on Monday following their arrests overnight.

Both were charged with aggravated counts of affray, robbery and assault.

Opposing bail, the prosecutor told court there was "a great sense of fear instilled in all shoppers who remained at Marion, as it took some time to determine the nature of the offending and the risk to the public".

"Brandishing items of this nature, being a machete and extendable batons, is something that's not trivial," he said.

"The risk to the public that's caused by persons engaging in wanton violence of this nature in such a public atmosphere causes great risk to public safety."

Earlier, the court was told the alleged robbery victim had noticed three males following him to the shopping centre and he feared they were about to take the Trap Star hoodie he was wearing.

"It's an expensive hoodie," the prosecutor said.

He told court the alleged victims and his friends went to the KFC outlet at the centre's food court, where there were about 100 people.

"(The alleged victim) observes the other three boys approach one of his three friends. The weapons are alleged to have been brandished by all three. The friend returned to the hoodie owner and indicated they were demanding his jumper," the prosecutor said.

"It's at that point that the accused has produced a machete and has pointed it towards the group."

The prosecutor said the trio, holding extendable batons, approached the two boys and demanded the jumper. The alleged victim and his friends then fled.

"After a short chase, the victim removed his hoodie and left it on the ground and sees that it's collected by the accused. The second victim ran towards Kmart and was being chased by the co-accused, and there was a strike to his leg with the extendable baton," the prosecutor told the court.

He said the trio fled through David Jones and exited the shopping centre.

The Westfield Marion Shopping Centre in Adelaide.
Teens allegedly with a machete and batons sparked a lockdown at Adelaide's biggest suburban mall. (HANDOUT/7 NEWS)

Centre management activated an alert and evacuation alarm, and the centre went into lockdown.

Shoppers sought refuge in stores as STAR Group officers searched for those involved.

At 11.45pm on Sunday, police executed a search warrant in the southern Adelaide suburb of Clovelly Park.

The prosecutor said police found unique clothing identified in CCTV worn by the alleged offenders and two extendable batons.

The two teens were arrested, with police still searching for a third person they believe was involved.

The 16-year-old's lawyer told the court the youth was unaware of the lockdown until hours later.

"The fear that's ultimately caused by Westfield ... it was never (the defendant's) intention that things escalated to the point they did, in so far as the response is concerned," she said.

The magistrate remanded the boys in custody, pending a bail report to assess their suitability for home detention.

The lockdown came 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.