The bus reportedly rolled down a slope to a river and some passengers were found trapped underneath.
Three people by the highway were confirmed dead while 16 other bodies were found by the river where the bus had rolled, according to ER24 paramedics spokesman Ross Campbell.
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A bus in northern South Africa crashed head-on with a van that left 20 dead and 68 injured. (Fox News)
"Most of the fatalities down the river had been trapped under the bus," said Campbell.
One more person died after being taken to a hospital, he said. Others injured received treatment at the site with some being transported to nearby health facilities for further care, he said.
While exact details surrounding the collision are unknown, heavy rains have been falling in the area, according to Campbell.
Police investigators were still on the scene on Tuesday morning, said Campbell.