Defence Minister Ernesto Justiniano said the blast occurred when "pyrotechnic material" detonated at an artillery regiment around 14:30 (18:30 GMT) on Friday. Viacha lies about 30km from La Paz. Emergency teams have been searching rubble and treating dozens of wounded.
Rita Nebraska, a local health official, told television broadcasters that between 10 and 15 people were believed to have died, a higher toll than the preliminary official count. She also warned there was a risk of further explosions and urged residents to keep at least 150m away from the military base.
Police described widespread damage to nearby homes, with many windows shattered by the blast. Officers said fireworks had been stored at the site, and the cause of the detonation is being investigated. A police spokesman outlined the storage of pyrotechnics at the barracks as part of the initial inquiry.
Viacha's local government declared three days of mourning following the incident. Hospital staff and emergency responders continue to treat the injured and assess structural damage in the surrounding neighbourhoods.
The immediate priorities are search and rescue, securing the site against further detonations, and establishing what led to the explosion. Authorities face the task of reconciling differing casualty reports while managing public safety around the military facility as investigators gather evidence.
