Protesters seeking jobs and better housing clashed with police for the third straight day in parts of the economic hub of Johannesburg and spread to the capital Pretoria, piling pressure on a government faced with weak economic growth.
Unrest dubbed "service delivery protests" has mounted, boding ill for President Jacob Zuma's administration at a time when he is under pressure over a cabinet reshuffle that triggered credit downgrades.
The persistence of poverty and joblessness 23 years after the end of apartheid is also stoking the anger, often targeting local governments tasked with provision of services many blacks were deprived of under white-minority rule.
On Wednesday, residents of an informal settlement in Laudium, west of Pretoria, blocked roads with rocks and burnt tires, demanding electricity be installed in their homes.
Tshwane metro police spokesman Superintendent Isaac Mahamba told eNCA television that the situation was now calm.
In Finetown, south of Johannesburg, demonstrators threw rocks and stones as police used rubber bullets and tear gas to disperse the crowds.
"The situation here is that we share plots of land. There is lack of jobs, there are no projects, the youth are just idle - there is absolutely nothing," said a community leader in Finetown who only gave his name as Vuyo.
The protests kicked off in Eldorado Park and Ennerdale townships, south of Johannesburg, on Monday and Tuesday and triggered disturbances between police and residents.
South Africa's economy grew by only 0.3 percent last year.
Unemployment is stubbornly high at 26.5 percent and many among the black majority population still lack running water, electricity, roads and schools long after apartheid's demise.
S&P Global Ratings and Fitch downgraded South Africa's credit rating to sub-investment last month, saying a recent cabinet reshuffle that saw respected finance minister Pravin Gordhan dismissed would likely result in a change in economic policy direction and hinder plans to stimulate economic growth.