Port Elizabeth - A municipal building in Kirkwood was set alight during service delivery protests on Tuesday, Eastern Cape police said.
Warrant Officer Basil Seekoei urged motorists to use alternative roads and members of the public to avoid the town's central business district.
Burnt tyres and wood were strewn along the town's main roads.
The protests began in the early hours of Tuesday morning, he said.
Rubber bullets were used to disperse the crowd.
“There were splinter groups and we had to control all of them simultaneously.”
Police were monitoring the situation. No arrests had yet been made.
Seekoei said the protest was linked to residents' unhappiness with the municipality and service delivery.
He could not confirm that the residents were from Moses Mabhida township, which was about 5km away.
By midday some of the protesters were still in the CBD.
Democratic Alliance MPL Vicky Knoetze said the Sunday's River Valley municipality had written off R84.5 million for irregular expenditure.
The municipality could not be immediately reached for comment.