LA PAZ, April 14 (Xinhua) -- At least six people were killed and another 14 injured on Tuesday when a passenger bus plunged into a ravine in the mountainous region of La Paz department in western Bolivia, authorities said.

The accident occurred in the Tolapampa district of Apolo municipality along a stretch of road worn away by seasonal rains. The direct causes of the accident are still under investigation, according to local media.

Apolo Mayor Rully Jimenez said local residents helped take care of the injured, several of whom remain in serious condition at city medical centers. ■