She said menacing men made eye contact with some concert-goers, as though to say, '"You could be next,"' and that there were no police in sight.
Joburg Public Safety MMC Michael Sun says this was above the city's mandate.
"The criminals were basically having a field day", said Zikhona Tshona, a reporter for the South African news organisation eNCA.
Global Citizen and another group backing the concert, the House of Mandela, urged South African police "to act swiftly and efficiently".
Sun said, "We will be working closely with SAPS to assist with the investigation and we also need to understand the cause of the problem so we can avoid this kind of incidences from reoccurring in future".
Ngodze was helping to set up the stage for the mega event which was held at the FNB stadium in Soweto on Sunday. "Our law enforcement agencies, especially the police, are expected to play their role and responsibility", he said. Cele said police had one case number for a stolen cellphone, but said that no other cases had been opened.
He said there was a stampede when someone pulled out a gun.
Witnesses took to social media to share how chaotic scenes unfolded at a Sasol garage outside FNB stadium, Briefly.co.za gathered.
"For the Global Citizen Festival, the stadium provided the venue, we provided logistical services and provided certain cleaning, as well as medical services".