He added another possibility of the fire's origin: an electrical short-circuit. Minister Leitao called it an "immeasurable tragedy" and admitted that help combating the flames arrived too late. He said there were only four guards on duty, adding the fire started in the rear, and it took the guards a while to detect the fire. When they did, it was already too late. He added that an in-depth investigation into the fire's cause will be required.

The flames tore through hundreds of rooms containing some 20 million artifacts. They ranged from fossils and the reconstructed skeleton of a dinosaur, to Roman frescoes and pre-Columbian Brazilian relics. Museum officials say almost 90% of the collection has been destroyed.