Eleven South African taxi drivers were killed and four others critically wounded when gunmen opened fire on their minibus.
Police Brigadier Jay Naicker said the victims were returning to Johannesburg from a colleague's funeral when they were ambushed between the towns of Colenso and Weenen in KwaZulu-Natal province.
Two people among the 17 on the bus were unscathed.
Police are investigating possible motives, but rivalry between groups of taxi drivers vying for the same routes has led to violence in the past.
South African media reported the deaths of 10 people in violence related to rivalries among minibus taxi drivers in Cape Town over one weekend in May.
Minibus taxis are an essential mode of transportation in South Africa.