Rousseff became teary-eyed as she spoke of the fire to reporters in Chile earlier Sunday. She had been attending a regional summit there, but cut short the trip and returned to Brazil early to deal with the aftermath of the tragedy.
"The Brazilian people are the ones who need me today," she said. "I want to tell the people of Santa Maria in this time of sadness that we are all together."
The fire started around 2 a.m. after the acoustic insulation in the Kiss nightclub caught fire, said Civil Defense Col. Adilomar Silva.
An accordionist who had been performing onstage with a band when the blaze broke out was among the dead, drummer Eliel de Lima told Globo TV.
Police were questioning the club's owner and interviewing witnesses as part of an investigation into what caused the blaze, state-run Agencia Brasil reported.
The club's license had expired in August and had not been renewed, local fire official Moises da Silva Fuchs told Globo TV.
The incident called to mind a 2003 nightclub fire in Rhode Island where pyrotechnics used by the heavy metal band Great White ignited a blaze that killed 100 people.
Pyrotechnics were also involved in a 2004 nightclub fire in Argentina that killed 194 people and a 2009 explosion at a nightclub in Russia that left more than 100 dead.