The chairperson of the Alexandra, Randburg, Midrand and Sandton Taxi Association (Armsta) and a second member were shot dead in Marlboro, Sandton on Thursday.
The association's John Mnisi said on Friday that Themba Sam Budza and member Fani Ramatfwane were gunned down late on Thursday afternoon while travelling home.
"We don't actually know what happened, but my understanding is that two cars came and started shooting at them. We are surprised ourselves," Mnisi said.
A third member survived the shooting and is recovering in hospital.
Police spokesperson Captain Kay Makhubela confirmed the shooting.
"We don't know the motive and we don't know the suspects."
Murder and attempted murder cases had been opened, Makhubela said.