The driver is among the survivors, local authorities say.
The bus was on its way from the village of Kami to the provincial capital of Cochabamba when the accident happened. Circumstances were unclear on Sunday night.
Serious traffic accidents are common on the narrow, often unpaved roads in Bolivia’s part of the Andes. In the last year, several buses have run off the road and fallen, with several dozen dead as a result.
In 2020, 1,096 people lost their lives in traffic accidents in Bolivia, according to the country’s Statistics Norway.