Gunmen in South Africa have killed 11 taxi drivers in an ambush, police say.

The men from Gauteng province were travelling to Johannesburg on Saturday night when their minibus was fired at.

The dead men, and four more who were critically injured, were returning from a colleague’s funeral in the coastal region of Kwa-Zulu Natal, police said.

The motive is unclear although rivalry between groups running minibus taxi routes in South Africa has led to violence in the past.

Minibus taxis are the most popular form of transportation among South Africa’s population of 55 million.