"It's bad now," said Warrant Officer Kay Makhubela.
"They have put a lot of things on the roads because they don't want cars entering Pimville."
Makhubela said traffic on Chris Hani Road had come to a standstill. No arrests had yet been made.
Residents were protesting against pre-paid water meters.
On Thursday night, protesters blocked the same road with burning tyres and rocks.
Some cars were pelted with stones but no one was injured.
The situation calmed down overnight but resumed in the morning.