At least 16 people were killed and 32 others injured when a bus plunged into a ravine on the highway that links La Paz to Bolivia's northern Amazon region, police and medical personnel said.
The accident happened on Thursday afternoon near Unduavi, a town about 46 kilometers (28 miles) from La Paz, when the bus went off the road and fell 120 meters (393 feet) to the bottom of the ravine, highway patrol chief Victorino Torrez told reporters.
"We have more than 16 dead, the highway patrol and the Bersa rescue team are working to recover the bodies," Torrez said.
La Paz's Arco Iris Hospital received 32 accident victims, with several listed in critical condition, hospital spokesman Dr. Fernando Arispe said.
The bus was carrying a group of students from Chicaloma, a town in Sud Yungas province, who were going to take part in a sports event in La Paz.
The government has been trying for years to reduce the number of traffic accidents in Bolivia.
President Evo Morales's administration enacted a law in January 2010 that cracked down on bus drivers caught working drunk, inexperienced drivers and drivers who work excessive hours.
The measure's goal is to reduce accidents, which kill an average of 1,000 people annually, according to International Automobile Federation figures, in this Andean nation. EFE