South African President Cyril Ramaphosa is expected to visit the sites of devastating floods that have left at least 78 people dead in the southeast of the country.

The death toll in floods in one of South Africa's poorest provinces rose to at least 78 on Thursday as a top official said rescue attempts in the first hours after the disaster had been "paralyzed" by a lack of resources.

The death toll included six high school students who were washed away when their school bus was caught in floodwaters on Tuesday near a river close to the town of Mthatha, which was especially