The accident occurred Saturday on the road to Challapata, a town about 250 kilometers (155 miles) from the main city of La Paz.
Col. Freddy Betancur, commander of the police in the central Oruro region, told The Associated Press: "There are seriously injured who have been transferred to the nearest hospitals."
Challapata Mayor Martin Feliciano told the AP that the death toll may rise.
A police report said that the accident was due to excessive speed and one of the buses may have driven into the oncoming lane.
Deadly bus accidents are common in Bolivia's highlands where narrow highways sometimes wind through mountain ranges near steep precipices.
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