Sparks apparently hit the soundproofing material on the ceiling which triggered the blaze, which quickly got out of control.

BBC: Could Brazil's club fire have been avoided?

Then, in the pre-dawn hours of Sunday, it turned into a scene of indescribable horror as sparks lit a fire in the soundproofing material above the stage, churning out black, toxic smoke as flames raced through the former beer warehouse, killing 231 people.

NPR: No Alarm, Only 1 Exit In Brazil Nightclub Fire