Santa Maria, Brazil (CNN) -- Guitarist Rodrigo Martins was preparing to launch into the sixth song of his band's set when he saw embers fall.
The acoustic foam insulation on the ceiling of the Kiss nightclub in the southern Brazilian city of Santa Maria was on fire, and it was beginning to spread.
The hot ash fell onto the stage and dance floor.
In front of him, a sea of people who moments earlier were dancing and singing along to the country-pop sounds of his band Gurizada Fandangueira began to realize something was wrong.
Suddenly, concertgoers were stampeding toward the club's only exit, pushing and shoving each other trying to get out.
Then, according to investigators and witnesses, somebody fell in the narrow, dark hallway that led to the windowless exit.
And then another person fell.
And then another.
Searching for answers
It was the last weekend of Brazil's summer break for many of the students, and the Kiss nightclub was packed early Sunday with young people, many of whom attended one of a number of universities and colleges in Santa Maria.
At least 231 people died and hundreds more were injured in the fire, which authorities believe began about 2:30 a.m. Sunday when the band's pyrotechnic show ignited insulation material.
Many apparently died from smoke inhalation. Others were trampled in the rush for the exits.
Of the dead, 101 were students at the Federal University of Santa Maria.
Another 120 remained hospitalized Monday morning, 79 in critical condition, authorities said.
About 2,000 people were inside the club when the fire broke out -- double the maximum capacity of 1,000, said Guido de Melo, a state fire official.
The roof collapsed in several parts of the building, trapping many inside. Firefighters found piles of bodies in the club's bathroom.
It looked, said state lawmaker Valderci Oliveira, "like a war zone."
For others, escaping was complicated by the fact that guards initially stopped people from leaving, said a reporter from CNN affiliate Band News, echoing comments from the state fire official.
"Some guards thought at first that it was a fight, a huge fight that happened inside the club and closed the doors so that the people could not leave without paying their bills from the club," the reporter, Glauber Fernandes, said.
But Rodrigo Moura, a nightclub security guard, said the fire moved fast.
"All of a sudden the fire just took off and was all around us. We tried to tell people to get out," he said.
Authorities have arrested three people in connection with the fire, state-run Agencia Brasil reported on Monday.
The owners of the nightclub, meanwhile, pledged to cooperate with the investigation into the fire, according to a statement released by the law firm of Kummel & Kummel.
"We are open to all authorities and inspections," said the statement, obtained by Globo TV.
The club's license had expired in August and had not been renewed, a local fire official told Globo TV.
The owners, however, said the nightclub was properly permitted and had been inspected by the fire marshal.
'Blocked by security'
The band, Gurizada Fandangueira, was a popular attraction at Kiss in part because of its pyrotechnic show, according to Billboard.com. It played at the nightclub about once a month, and was there Sunday to promote a new album.
Martins, the guitarist, told Radio Gaucha the band had been on stage for about 20 minutes, finishing the fifth song of its set, when it set off its "sputnik" pyrotechnics -- sparkler columns that shoot up in the air.
"We used it all the time. ... We never had this problem before," he told the radio station late Sunday.
Martins said he first noticed a small ember, and then he looked up at the ceiling and saw the flames.
A backstage hand attempted to put out the blaze with a fire extinguisher. "But it didn't work," he said.
Martins said as he and the other band members got off the stage, there were 20 to 30 people in front of him who were "being blocked by security."
People started pushing and shoving, and then they tripped over one another trying to get to the door.
Martins said the band's accordion player, 28-year-old Danilo Jacques, died in the fire. "I saw him, and then I lost him in the crowd."
Struggling to help
Esequiel Corte Real and his friends arrived late for the show and ended up with what they thought was one of the worst locations to watch -- by the exit.
The same happened with Norton Basson and his friends, who were at the club to celebrate his 29th birthday.
They are alive, they believe, because of where they were -- making them among the first to make it out alive.
After the fire started, the dark, narrow hallway that led to the nightclub's exit was choked with smoke and people trying to find their way out.
Outside, Corte Real and his friends could hear the screams of people trying to escape.
He told Globo TV that he and his friends ran back into the club to try to help.
They pulled out one body. Then two more.
"Somebody must be alive," he said.
Basson and his friends, meanwhile, grabbed rocks, sticks and an axe they found at a nearby building and began trying to knock a hole in the side of the club to help those trapped inside. Others soon joined them with shovels and more axes.
Firefighters used the hole Basson and his friends created to get inside the club.
There, they were greeted by the eerie sounds of cell phones ringing in the pockets and purses of the dead. Many of the calls were from parents desperate to reach their children.
Later Sunday, family members wept as they searched for information outside a local gymnasium where bodies were taken for identification.
Inside, Brazilian President Dilma Rousseff met with relatives as they waited on bleachers for word of their loved ones. She had been attending a regional summit in Chile, but cut short the trip and returned to Brazil early to deal with the aftermath of the tragedy.
"The Brazilian people are the ones who need me today," she said. "I want to tell the people of Santa Maria in this time of sadness that we are all together."
Ericmar Avila Dos Santos went from hospital to hospital Sunday, searching for his 23-year-old brother.
Hours earlier, he learned in a telephone call from a friend that his older brother was among those missing following the fire.
His family scanned lists, talked with police officials. They checked with friends, searched everywhere.
They finally found him -- among hundreds of bodies laid out on body bags at a makeshift morgue at a local gym.
"I was supposed to go with him. I didn't feel like going out. He ended up there without me," Avila Dos Santos said, openly sobbing over his brother's coffin outside the gym.
On Monday, the first of Brazil's three days of mourning, the three cemeteries in the city of 260,000 were packed with families readying to bury their dead.
Among them was Avila Dos Santos' family.
"We did everything together. We were even studying the same major," he said, remembering his brother. "Now that he's gone, I'm lost. I don't know what I'm going to do with my life."
Shasta Darlington reported from Santa Maria, Brazil. Chelsea J. Carter reported from Atlanta. CNN's Helena DeMoura contributed to this report.