Just before 3pm, two groups of young males were embroiled in a fight in the food court of Westfield Marion.
Some of them are believed to have been carrying weapons.
Police said the brawl was not believed to be random.
Officers have since arrested a 15-year-old boy from Morphett Vale this morning.
Police have said he will front a youth court as soon as possible.
Last night, two boys, aged 15 and 16, of Mitchell Park and Adelaide, were arrested.
The duo appeared in a youth court today.
All three were charged with assault, affray and aggravated robbery.
“It will be alleged the incident arose as a result of a robbery of clothing from one of the victims,” South Australia Police said in a statement.
Yesterday the shopping centre went into lockdown, with shoppers and bystanders urged to evacuate.
“Everyone was running for their lives,” shopper Janet Raphael said.
Police could not initially find the people involved in the fight but escorted several shoppers to safety.
Those inside shops were kept there for multiple hours as officers told them they were hunting the offenders.
“My partner and I were in David Jones near the jewellery section and we heard someone over Westfield (speakers) say ‘this in an emergency’,” another shopper told 9News Adelaide.
“Next minute the David Jones security doors went down.”
It is understood two shoppers were injured during the evacuation, including a 77-year-old woman who fell and suffered a fracture, along with a teenager girl.
The investigation is ongoing.