Two people - a police officer and a passenger - were wounded on Tuesday night when occupants of a minibus taxi opened fire on a Rea Vaya bus.

They were in a stable condition on Wednesday morning, reported news agency Sapa.

Sunday's launch of the Rea Vaya bus rapid transit system was met with strong opposition from certain taxi organisations, such as the South African National Taxi Association.

"We condemn in the strongest possible terms the violence that occurred in Soweto," said City of Johannesburg member of the mayoral committee for transport Rehana Moosajee in a statement released on Tuesday night.

"The city has been in touch with all spheres of government, and we remain firm in our resolve to continue the Rea Vaya BRT starter service.

"All law enforcement agencies are stepping up their measures to protect passengers, Rea Vaya staff and property.

"They have also indicated to us their determination to bring the perpetrators to book."

Moosajee said the continuing measures to protect commuters would include a police presence on all buses, as well as law enforcement vehicles accompanying the buses.

The council reported on Wednesday morning that the Rea Vaya service was running normally.

"All the buses and stations were operational, and passenger volumes remained the same as yesterday," said Moosajee.