Nurses and patients at a clinic in Bonabona in the North West were locked up during a service delivery protest on Tuesday, police said.
Lieutenant-Colonel Lesego Metsi said about 60 protesters brought their own locks to shut the clinic's doors.
“We are still trying to free the trapped people.”
Police were keeping an eye on schools and other essential services should protesters turn their attention elsewhere.
Earlier, the police stopped the same group from looting Somali and Pakistani shops.
“These people were targeted because they have managed to rent houses where they are running their tuckshops,” said Metsi.
Bonabona is outside Morokweng village near Vryburg, in the central part of the province.
“The situation is very volatile,” said Metsi.
Closer to Rustenburg, at Nkaneng informal settlement near the Bleskop mine, 4000 people protested around 4am against a lack of service delivery.
Metsi said this group wanted to speak to the Rustenburg mayor.
“They claim their own councillor was not doing his job properly.”
Metsi said the protesters wanted access to water, electricity and housing. They burned tyres and blocked the road to the mine, but were not violent, said Metsi. – Sapa