Eleven people were killed and four critically injured after unidentified gunmen opened fire on a minibus carrying a group of taxi drivers from a funeral in southeastern South Africa late on Saturday.

The taxi drivers, who belonged to Gauteng province's taxi association, were returning home to Gauteng after attending a funeral of a colleague in neighboring KwaZulu-Natal province. The ambush took place between the KwaZulu-Natal towns of Colenso and Weenen.

Read more: South African policemen sentenced for taxi driver murder

"There has been a lot of taxi violence in the area but we are still investigating who the perpetrators were," province spokesman Jay Naicker said.

Minibus taxis are the most popular form of transport in South Africa and violence between rival associations over lucrative routes has plagued the country for years.

Ten people were reportedly killed in deadly clashes between taxi groups in western city of Cape Town in May.

amp/rc (AP, dpa, Reuters)