Brazil's president declared such a tragedy must never be allowed to happen again.
Most of the marchers wore white shirts and carried white flowers and white balloons, as well as placards of the victims' names, as they walked more than a mile Monday night from a large square in the center of the college city of Santa Maria in Brazil's southernmost state of Rio Grande do Sul.
Many people held hands and embraced each other during the somber walk. Violinists played Franz Schubert's "Ave Maria" and other prayerful music, the Folha de S. Paulo newspaper reported. At one point a large group started singing the Rio Grande do Sul state anthem, and there were bursts of applause in memory of the victims, the newspaper said.
In front of the Kiss nightclub, scene of the 2:30 a.m. Sunday tragedy, people shouted: "Justice! Justice! Justice!" the newspaper O Globo reported.
The street in front of the nightclub still gave off a strong smell of burning, the newspaper said.
Many marchers continued to past the club to a municipal sports center that served as a makeshift morgue for the dead and a holding area for relatives Sunday in the hours after the inferno.
Some sang Brazil's national anthem as they approached the center, Folha reported. Inside, people sat on gym bleachers that had been used for immediate family of the dead the day before and raised the placards during a memorial service. At one point people burst all the balloons, Folha said.
The service at almost midnight followed a marathon of funerals Monday. At least 101 of the dead were students at the Federal University of Santa Maria who had been out at the nightclub celebrating the last weekend of summer vacation before returning to classes.
Most died asphyxiated, police said. Many were found crammed in or near bathrooms to the side of the nightclub stage. Investigators theorize they were desperately looking for an emergency exit as access to the main door had become clogged with people trying to get out. But there was no exit there.
"They were young. Had dreams. Could be our future mayors," President Dilma Rousseff told 26 mayors and 28 ministers at a national mayors conference in Brasilia, the capital.
"Mayors, chairmen and presidents, scientists, agronomists, psychologists and judges," Rousseff said. "They could be the sons, daughters, grandsons and granddaughters of each one of us."
She spoke of the "indescribable" pain she witnessed and felt when she met with parents of the dead at the sports center Sunday.
"We have a duty to ensure that it will never happen again," Rousseff said.
Authorities held four people linked to the fire -- two of the nightclub owners and two members of the raucous Brazilian country music band Gurizada Fandangueira -- to avoid manipulation of evidence, law-enforcement officials said late Monday.
The owners held are Elissandro Spohr, known as "Kiko," and Mauro Hoffmann, authorities said. The two ban members are lead singer Marcelo de Jesus dos Santos, alleged to have detonated the flag that caused the fire, and production engineer Luciano Bonilha, responsible for the stage direction and stage setup.
The band members were taken into custody in a town about 40 miles from Santa Maria, police said. Spohr was found at a clinic about 80 miles away. Hoffmann turned himself in Monday afternoon, police said.
Lawyer Mario Cipriani, who accompanied Hoffmann, said his client was simply a passive investor and had thought the club was up to code and meeting legal standards.
State police investigator Marcelo Arigony said the club's permits were expired at the time of the fire. He said they may not have been lawful in the first place, considering the club had only a single exit.
Investigators also were probing if the pyrotechnic show was in line with fire-safety laws, police said.
The four detained men would be held for five days, and could be held for another five days, with a judge's order, police Chief Marcelo Arigony said.
Holding the men is part of efforts to push the investigation forward, a legal power available to Brazilian courts, and didn't necessarily mean the men would be charged, Arigony said.
"We're not trying to point fingers at this point, but the elucidation of fact," he said.
Prosecutor Joel Oliveira Dutra said it was possible evidence would suggest the detainees should be charged with involuntary manslaughter. He was also considering the possibility that acts of omission by the detainees could upgrade the charges to voluntary manslaughter, O Globo reported.
A judge Monday night allowed for an injunction holding all the club owners' assets to ensure future compensation to the victims' families and to survivors suffering physical and emotional stress from injuries in the tragedy, the Zero Hora newspaper reported.
Altogether, 231 people died and another 80 remained hospitalized.
The fire had started in the foam soundproofing the club after a band member allegedly used a Roman candle or emergency traffic flare to ignite a flag. Sparks that hit the ceiling started the fire, witnesses said. The band's guitarist said the fire extinguisher did not work.
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