Brazilian President Dilma Rousseff cut short a visit to Chile, where she was attending a European and Latin American summit, to head to Santa Maria and oversee the response to the tragedy, a Brazilian official said.
It was not immediately clear what caused the blaze, but media reports said the fire broke out early morning when the nightclub was hosting a university party featuring a rock band using pyrotechnics.
Santa Maria fire chief Guido de Melo said the fire caused widespread panic, and that many revellers were trampled or died from smoke inhalation.