The Agencia Boliviana de Informacion said the accident happened Sunday about 43 miles southeast of the capital La Paz near the city of La Florida, CNN reported.
The U.S. broadcaster said Bolivia's ATB TV showed video of rescue workers clambering down sheer mountain faces on ropes to reach the wreckage. One survivor told the Bolivian network that the bus appeared to hit an object on the road and lost control of the vehicle.
The state news service said heavy vegetation around the around the accident site hampered the rescue efforts.
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