People march in tribute to the victims of the Kiss nightclub fire in the southern city of Santa Maria, 187 miles (301 km) west of the state capital Porto Alegre, January 28, 2013. [Photo/Agencies]

SANTA MARIA, Brazil - Brazilian police investigating a nightclub fire that killed 231 people detained on Monday the owners of the club and two band members whose pyrotechnics show authorities say triggered the blaze as the focus turned to finding those responsible for the tragedy.

No charges were filed against the four men, but prosecutors said they could be held for up to five days as police press themfor clues as to how the fire early Sunday morning could have caused so many deaths.

Stunned residents in the southern city of Santa Mariaattended a marathon of funerals beginning in the pre-dawn hours. As sunset approached, friends and family members readied for a candle-lit procession through the streets of the city.

The tragedy came as Brazil prepares to host the 2014 World Cup soccer tournament and 2016 Olympics, putting its safety standards and emergency response capabilities in the international spotlight.

President Dilma Rousseff, who cut short a visit to Chile tofly to the scene of the disaster on Sunday, called for a minute of silence before addressing a meeting of newly elected mayors in the capital, Brasilia.  

"The pain I saw in Santa Maria was indescribable," Rousseff said. "Faced with this tragedy, it is our duty to make sure it never happens again."

Most of the dead were suffocated by toxic fumes that rapidly filled the Kiss nightclub after the band set off a flare atabout 2:30 am on Sunday, authorities said.

The club's operating license was under review for renewal after expiring last year.

Witnesses said bouncers initially blocked the only functioning exit because they believed fleeing customers were trying to skip out on their bar tabs.

Tarso Genro, governor of the prosperous southern state ofRio Grande do Sul where the disaster occurred, said authorities had shifted their focus from rescue and taking care of thewounded to investigating the scene.

"We're going to find out who was responsible," he vowed.

The death toll was revised down to 231 from 233 as officials said some names had been counted twice. Eighty-two people were hospitalized, 75 of them in serious condition, officials said.

Mourning throughout Brazil was mixed with frustration at aculture of lax regulation blamed for putting lives at risk.

"So many young ones with all of their lives ahead of them,"Brazilian soccer legend Pele wrote on Twitter. "The government has to make a priority of event security in this country!"