The Johannesburg Metro Police Department (JMPD) arrested seven people allegedly linked to several muggings and attacks after the Global Citizen Festival at FNB Stadium on Sunday.
The JMPD said it understood many of the muggings reported on social media pointed to a gang of thugs attacking and robbing concert goers at or near a fuel garage, which was about 1.4 kilometres away from FNB Stadium.
Scores of concertgoers took to social media on Monday to express their dissatisfaction at security at the concert.
Some said gangs of juveniles attacked and stabbed them before robbing them of cellphones and handbags.
The City of Johannesburg's member of mayoral committee for public safety, Michael Sun, said he was shocked to hear about the incidents and stressed that the City was talking to police to establish what happened because they were responsible for overall policing at the festival.
"We have learnt that only one incident was formally reported, which goes in stark contrast to the many reports surfacing all over media," Sun said.
"We want to express our deepest regrets to those affected and call on the victims to come forward and report any incidents to the SAPS so investigation can be undertaken."
Sun added that the event's safety and security planning committee had established a "safe zone" where concertgoers should have been picked up by e-hail taxis, and said that this might not have been conducted as planned.
"It is suspected that the e-hail taxi operators may have requested some of their passengers to walk to the nearby Sasol garage to be picked up, which was outside the safe zone," Sun said.
He said the City would assist with the police investigations.
Sun pointed out that world-renowned band Guns and Roses attracted nearly 65 000 fans to their concert at the same stadium just three days before and the event was an overall incident-free one - except for a report of suspected domestic violence.