Buses and taxis were stoned by residents of Motherwell near Port Elizabeth on Wednesday, Eastern Cape police said.
Captain André Beetge said violence flared up at about 6.20am in Ngonyama Street in Motherwell.
Two police officers saw people breaking the windows of Algoa buses and climbing out of the vehicles through the windows and the door.
About 50m further, police saw the windows of another bus being broken from the inside and people exiting through the broken windows.
Three shots were fired at police. No one was injured during the shooting.
The attack started by targeting buses but then spread to taxis and then cars. Commuters were stranded and became angry, which led them to join in the stoning action.
Buses and taxis were taken out of the suburbs under police escort.
Beetge said police had reacted early and managed to calm the situation down. He said at about 11am that he believed the worst had passed and hoped Thursday would be better.
A strong police presence was being maintained.
Beetge called on employers to allow their employees grace because many of them were unable to get transport to work.
He described the start of the incident as coordinated, saying it started in many areas at roughly the same time. The attacks seemed aimed at bringing public transport to a halt, he said.
Police believe the attack may have been discussed before the time.
Beetge was unable to say whether a specific group had been responsible but added he was waiting for reports to establish the scope of the incident.
He confirmed that one attempted murder case relating to the shooting was being investigated.
A protest had been scheduled to take place in Port Elizabeth over public transport and new minibuses in preparation for the 2010 Soccer World Cup. It was not clear if the protest action had any bearing on the Motherwell incident. — Sapa