Police fired rubber bullets at rowdy ANC Youth League supporters who tried to force their way into the ANC's headquarters on Tuesday where Julius Malema faced a disciplinary hearing.
Police sprayed water and fired teargas at his supporters, who were running amok and throwing bottles at law enforcement officials.
A cameraman had to run away and hide behind a wall after a brick was thrown at him.
A heavy police contingent cordoned off Luthuli House building, where the ANC Youth League leader and several other top leaders faced charges of bringing the ruling party into disrepute.
According to tweets from the scene, violent clashes erupted between ANCYL supporters and police. Bricks, stones and bottles have also been hurled at television crews.
Several streets were closed while groups of supporters, whistling and blowing on vuvuzelas, ran up and down, signalling to motorists to stop and make U-turns.
One of the supporters told a Sapa reporter they were running around to show the police they were not scared of them, and that they would force their way into Luthuli House if the disciplinary hearing went against Malema and his co-accused.
Beyers Naude square, where portable toilets had been set up, was strewn with litter following a night vigil.
A helicopter hovered over the crowds while police would not allow anyone near the Luthuli House building.
"The numbers are swelling," said Johannesburg metro police spokesperson Wayne Minnaar.
"Sauer street is blocked off at Market street, Simmonds street is blocked off at Pritchard street and Harrison street is blocked off at Pritchard street."
Malema faces charges alongside league spokesperson, Floyd Shivambu, league deputy president Ronald Lamola, secretary general Sindiso Magaqa, his deputy, Kenetswe Mosenogi and treasurer general Pule Mabe.
The charges include bringing the ANC into disrepute and sowing divisions in ANC ranks.Promises of discipline
Earlier, an ANC Youth League leader of Ekurhuleni promised that supporters would stay disciplined on Tuesday, as crowds grew outside the ruling party's headquarters.
"We will not cause confrontation with police...we are staying together united and disciplined. We are not going to break anything," said Thepelo Khumalo, chairperson of the ANC Youth League's Tsakane branch in Ekurhuleni.
He said his branch members arrived in five Toyota Quantums.
"We did it for President Jacob Zuma so now we are doing it for Julius Malema... we support everyone in Luthuli House...
"He [Malema] is the son of the president."
Members who converged around him said they did not believe the charges brought against their president meant that Zuma was going against Malema.
Should "the big 5" be suspended, Khumalo said the elders would have to suspend all members of youth league.
"Malema is our mouth, he took a mandate from us...if he is suspended, we are going with him in solidarity."
One member was draped in chains across his chest. He strode across Beyers Naude square, carrying a placard saying: "Julius Malema ons stan by jour [sic]. Deur dik en dun! [Malema, we stand by you through thick and thin.]"
Khumalo was one of Malema's supporters who had gathered at Luthuli House in Johannesburg to show support for Malema and his co-accused.
Hundreds of people had gathered and busloads more were expected.