"We have confirmed that is the final number for fatalities," spokesperson for the Western Cape health department Faiza Steyn said.
Eight people, including three children, were critically injured, 14 were seriously injured and 44 sustained minor to moderate injuries, she said.
Western Cape traffic chief Kenny Africa said the bus was on its way to Cape Town when the bus driver lost control.
"There are still people trapped in the bus, as well as the driver, and we are pulling up the bus now," he said.
ER24 spokesperson Vanessa Jackson said the double-decker bus was crushed against the side of the mountain along the pass.
The Inkatha Freedom Party (IFP) sent its condolences to the families of those who had died.
"This is a terrible tragedy. We urge people to be extra cautious when it is raining and to follow all the rules of the road," IFP spokesperson Petros Sithole said.
"The traffic cops and police should investigate whether the bus was overloaded and if so, we would expect the necessary criminal charges to be laid against the bus driver," Sithole said. – Sapa