Brazil has declared three days of national mourning for 231 people killed in a nightclub fire in the southern city of Santa Maria, reports BBC.

The fire reportedly started after a member of a band playing at the Kiss nightclub lit a flare on stage.

Authorities say most of the victims were students who died of smoke inhalation. The first funerals are expected on Monday morning. It is the deadliest fire in Brazil in five decades.

Brazil postponed a ceremony due on Monday in the capital, Brasilia, to mark 500 days to the 2014 football World Cup. In Santa Maria, 30 days of mourning were declared.

President Dilma Rousseff, who cut short a visit to Chile, has been visiting survivors at the city's Caridade hospital along with government ministers. "It is a tragedy for all of us," she said.

Authorities have released the names of the victims, after revising down the death toll from 245.

More than 100 people were being treated in hospital, mostly for smoke inhalation.

Officials will now investigate reports that a flare was lit on stage, igniting foam insulation material on the ceiling and releasing toxic smoke.

They will also look at claims that many of those who died were unable to escape as only one emergency exit was available.

The fire broke out as students from the city's federal university (UFSM) were holding a freshers' ball, the Diario de Santa Maria, a local newspaper, reported.

A local journalist, Marcelo Gonzatto, told the BBC that the flare had "started a huge and fast fire that grew quickly and made a very dark and heavy smoke."

"Lots of people couldn't get out and died mainly because of the smoke not the fire," he said.

Witnesses spoke of scenes of panic after the fire started, and a stampede as people tried to escape.

One, Mattheus Bortolotto, told local television: "It was sheer horror. The emergency exits did not work, and then I lost my friend in the confusion. Then a girl died in my arms. I felt her heart stop beating."

A large number of victims were trapped in the club's toilets, they said, possibly after mistaking them for an exit.

Survivors and police inspector Marcelo Arigony said security guards briefly tried to block people from leaving the club, the Associated Press news agency reported. Bars in Brazil commonly make customers pay their whole tab at the end of an evening before they are allowed to leave.