An investigation is under way into a fire that killed at least 230 people and injured 200 others after a pyrotechnics malfunction at a nightclub in the southern Brazilian city of Santa Maria, officials say.

President Dilma Roussef declared a three-day national mourning period starting on Monday. Brazil also has cancelled celebrations in the capital Brasilia to mark 500 days before the 2014 World Cup.

"It is a tragedy for all of us. I am not going to continue in the meeting [in Chile] for very clear reasons,'' Roussef said before arriving in Santa Maria, where she met families of the victims.

Police Major Cleberson Braida Bastianello said officials counted 232 bodies that had been brought for identification to a gymnasium after the blaze erupted early on Sunday.

Bastianello said that they lowered the toll from 245 earlier believed killed at the Kiss nightclub.

The identification process of the bodies had been completed by early on Monday, Al Jazeera's Teresa Bo reported from Santa Maria.

Major Gerson da Rosa Ferreira, who was leading rescue efforts at the scene for the military police, said the victims died of asphyxiation or from being trampled.

Investigators are looking into reports of overcrowding inside the club, according to Al Jazeera's Gabriel Elizondo, who is also reporting from Santa Maria.

He said there were reports that as many as 1,000 to 2,000 people in their 20s were at the club when the fire broke out.

Some witnesses also reportedly claimed that security at the club initially shut down the main entrance, preventing people from making a quick exit, Elizondo said.

Underage visitors

Investigations suggested that there was only a single exit door in the crowded nightclub, and that in the confusion immediately after the fire broke out, it was initially shut by staff, she said.

Authorities also say that many of those who died were between 16 and 20 years old, and were reportedly allowed inside the club even though they were underage, Al Jazeera's Bo said.

Santa Maria is near the borders with Argentina and Uruguay, about 300km west of the state capital of Porto Alegre.

Luiza Sousa, a civil police official in Santa Maria, told Reuters news agency the blaze started when a member of the band or its production team ignited a flare that then set fire to the ceiling, which was apparently covered with insulating foam.

The fire spread "in seconds", Sousa said.

Sandro Meinerz, a police inspector, told the Agencia Estado news agency that manslaughter charges could be filed against the band, at least one of whom died in the fire, or their crew.

Television images showed black smoke billowing out of the Kiss nightclub as shirtless young men who had attended a university party joined firefighters using axes and sledgehammers to pound at windows and exterior walls to free those trapped inside.

Bodies of the dead and injured were strewn in the street and panicked screams filled the air as medics tried to help. There was little to be done; officials said most of those who died were suffocated by smoke within minutes.