SANTA MARIA, Brazil: Brazilian police on Monday detained the owners of the nightclub where a fire killed 231 people as well as two band members whose pyrotechnics they 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 pressed them for clues as to how the fire early Sunday morning could have caused so many deaths.

Stunned residents in the southern city of Santa Maria began attending a marathon of funerals in the pre-dawn hours of Monday. Many of the dead were university students who knew each other.

Coffins, many draped with flags of the victims' favorite soccer teams, lined a gymnasium that has been used as a makeshift morgue.

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

The club's operating license was in the process of being renewed after expiring last year, and 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 of Rio Grande do Sul where the disaster occurred, said police had taken the men into custody to ensure "this will never happen again."

Genro said authorities' focus had shifted from rescue and taking care of the wounded 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 remained hospitalized, at least 30 of them in serious condition.

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 visited the scene, visibly upset, on Sunday.

Relatives and friends of the dead demanded accountability, signaling the start of a wave of police probes, lawsuits and recriminations that could drag on for months or even years.

"We can't trust in the ability of city hall, or the police, or anybody who permits a party with more a thousand people under these conditions," said Erica Weber, who was accompanying her daughter to a funeral for one of her classmates.

Based on testimony from more than 20 witnesses, investigators are now certain that the band's pyrotechnics show triggered the blaze, said police official Sandro Meinerz. He added that initial reports that the club was operating beyond its capacity of 1,000 people were likely false.

"Witnesses said the club wasn't as full as it had been in previous weeks, which surely avoided an even greater tragedy," Meinerz said.

The band's guitarist, Rodrigo Lemos Martins, 32, said he doubted the band was responsible for the blaze. "There were lots of wires (in the ceiling), maybe it was a short circuit," Folha de S.Paulo newspaper quoted him as saying.

The band's accordion player, Danilo Jaques, 30, was among those killed but the other five members survived. Vocalist Marcelo de Jesus dos Santos and production engineer Luciano Bonilha, who police believed were responsible for firing the flare, were taken into custody, according to Brazilian media.

It seems certain others will share the blame for Brazil's second-deadliest fire ever. The use of a flare inside the club was a clear breach of security regulations, fire officials said.

Some details may never be known. Meinerz said the club's internal video surveillance system had stopped working three months ago, according to the club owner.

Clubs and restaurants in Brazil are generally subject to a web of overlapping safety regulations, but enforcement is uneven and owners sometimes pay bribes to continue operating.

The investigation of the Kiss fire could drag on for years. After a similar fire at an Argentine nightclub in 2004 killed 194 people, more than six years passed before a court found members of a band criminally responsible for starting the blaze and causing the deaths.

That tragedy also provoked a massive backlash against politicians and led to the removal of the mayor of Buenos Aires.

Civil lawsuits stemming from the Brazil fire are likely to be directed at the government because the owners of the nightclub probably don't have much money, said Carlos Castello de Campos, a Brazilian lawyer who has handled big cases including the crash of a TAM Airlines jet in Sao Paulo in 2007.

Castello de Campos disputed some local officials' claims that the Kiss nightclub could have continued operating legally while it was waiting for its license to be renewed. "If the license was expired, that's an irregular situation," he said.

Valdeci Oliveira, a legislator in Rio Grande do Sul state, said he and his colleagues would seek to ban pyrotechnics displays in closed spaces such as nightclubs.

"It won't bring anybody back but we're going to introduce the bill," Oliveira said on his Twitter feed.

The Brazil fire is the worst to hit an entertainment venue since a fire on Christmas Day in 2000 engulfed a mall in Luoyang, China, killing 309 people.