A bomb has caused an explosion that killed four people and wounded 10 during Carnival celebrations, Bolivian authorities say.
The blast occurred late on Tuesday in the middle of Carnival celebrations in the city of Oruro, the capital of President Evo Morales' home province.
Police Gen Faustino Mendoza told reporters the bomb was made of dynamite, ammonium nitrate and fuel oil, all commonly used in homemade explosives.
On Saturday night, an explosion along the Carnival route two blocks from Tuesday's attack killed eight and injured 40. Police had blamed the first explosion on a food vendor's gas canister, but said they were re-evaluating that in the wake of the second attack.
An ally of Morales publicly implied that opposition forces were behind the attack, while opposition members urged government supporters to refrain from blaming anyone without evidence.
"If the explosion is an action by the ultra-right, what's underway is a conspiracy against democracy," Hugo Moldis, a former member of Morales' administration, said on Twitter.
Australian Associated Press
