At least 11 taxi drivers were killed and four others critically injured after gunmen opened fire on a minibus carrying the group from a funeral on Saturday, officials said.
The South African Police Service the group was attacked in between the towns of Colenso and Weenen in the eastern part of the country.
Police Brig. Jay Naicker told the Associated Press the victims attended a colleague's funeral and were returning home when the ambush occurred.
Detectives are investigating possible motives for the shooting, and said the victims are from the Gauteng province.
Minibus taxis are the most popular form of transport in South Africa, violence is common by rival groups vying for dominance on profitable routes, according to Sky News.
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.
The Associated Press contributed to this report.