Updated

Bolivian authorities now say that both of the explosions that killed 12 people during recent Carnival celebrations were caused by dynamite, not exploding gas tanks as initially thought.

Interior Minister Carlos Romero says officials are still trying to determine who planted the explosives in the city of Oruro, and why.

He says both the Feb. 10 and Feb. 13 explosions were caused by 3 kilograms (6.5 pounds) of dynamite. Until now, officials had blamed the initial blast on a street vender's leaking gas line.

Romero said Sunday that police also have found a small piece of dynamite in a hotel bathroom in the city, which is about 120 miles (190 kilometers) south of the capital, La Paz.

It's a mining area where dynamite is widely available.