The explosion occurred at a facility in the centre of the city of Viacha, southwest of La Paz. Images in Bolivian media show a fireball shooting from the buildings into the sky.
Initially, authorities reported that two people had died, seven were missing and more than 80 were injured. A local health director said on television that 10 to 15 people were feared dead, Reuters reported.
The explosion is reported to have occurred in or near a storage facility containing some form of explosive material or fireworks.
The police have cordoned off the residential areas around the site. The mayor of Viacha has declared three days of mourning in the city, reports the newspaper La Razón.
