RIO DE JANEIRO — The assailants arrived in the sleepy city in southern Brazil just before midnight ready for battle: They wore head coverings and body armor, and were armed with powerful rifles and loads of explosives.
Over nearly two hours, the gunmen held the city of Criciúma hostage, shattering the nighttime calm with explosions and volleys of gunfire. They used people as human shields while they detonated explosives at a bank, sending a plume of bills flying into the air, and shot at an overwhelmed police force.
“It was a surreal scene,” said Clésio Salvaro, the mayor of the city of about 220,000, said in a televised interview Tuesday morning. “The city was left in a state of panic.”
The audacious attack on Criciúma was the latest in Brazil to target a relatively small city with poor defenses, where security analysts say they have good odds of overpowering and dodging security forces that deal mainly with petty crime. Criminals have carried out a handful of similar attacks in such places this year, rather than in the metropolises where large, well-equipped police forces have experience battling violent crime and powerful gangs.
Early on Wednesday, Brazilians reported online that heavy gunfire had erupted in the town of Cametá, which is more than 2,000 miles north of Criciúma and is in the northern state of Pará. Social media users said that a gang of men was staging another bank robbery, and the public security secretariat of Pará confirmed on Twitter that it had been notified of a robbery in progress.
“An assault is taking place right now in the city,” Renan Brites Peixoto, a reporter for GloboNews, said on Twitter. GloboNews reported that some barracks of the Military Police in Pará had also been attacked.
Helder Barbalho, the governor of Pará, said on Twitter that he had been in contact with the security authorities over an “episode” in Cametá, and that he would work to “ensure that peace is resumed as soon as possible.” He did not elaborate. The siege later appeared to end less than two hours later.
Samira Bueno, the executive director at the Brazilian Forum of Public Safety, noted that the Criciúma attack was one in a string of brazen assaults on banks in recent years that appear to be ripped from “the scene of a movie.”
They stand out even in a country with some of the highest crime and homicide rates in the world, where bank robberies are hardly uncommon. In recent years, gangs have attempted to dig their way to millions through tunnels, detonated dynamite to rob banks and have blown up cash machines.
In this latest assault, analysts said a team of roughly 30 gunmen arrived in a convoy of 10 vehicles from outside the state, Santa Catarina, and had planned the operation meticulously. Officials have not said how much money they made off with.
Ms. Bueno said it was striking how police officials were unable to stop the attack.
“It’s curious to see how unprepared the security forces were to deal with this incident,” she said. “Clearly it was the work of a group that is highly organized and specialized.”
Elected officials looked weary and shellshocked when they addressed reporters Tuesday morning at a news conference.
“The operation was successful for the criminals, that’s the truth,” Santa Catarina governor Carlos Moisés da Silva said.
Police officials in Santa Catarina said the gunmen opened fire outside the 9th battalion of the military police, which oversees security in the city, before heading downtown and taking aim at the local branch of the Bank of Brazil.
The gunfire left a security guard and a police officer wounded. Police officials said the officer underwent surgery and described his condition on Tuesday morning as “serious.”
“The criminals clearly planned, prepared and invested beforehand,” Anselmo Cruz, a police supervisor, told reporters Tuesday morning. “This points to a group that came from outside. We don’t have criminals with this profile in Santa Catarina.”
There are several drug trafficking gangs in Brazil that have carried out sophisticated robberies, but the authorities did not point to any of them as suspects.
Several residents of Criciúma who were shaken from their sleep by the blasts and bursts of gunfire managed to record snippets of the attack from windows and balconies using cellphones.
Some photos and videos showed men sitting in a file along a street. Local news reports described them as a human shield that prevented police vehicles from reaching the bank.
Daniel Freitas, a congressman who lives near the bank that was attacked, said he assumed the bursts that awoke him and his family were fireworks.
“What happened was unprecedented for people from Criciúma and Santa Catarina,” he said. “The shooting was unrelenting. It was constant gunfire and bombs.”
Bruno Adriano Della, a 20-year-old resident, said he had been woken up by gunfire.
“The whole city was in shock, and with gunshots everywhere. Nobody knew what to do,” he said. “We were just praying that it would end.”
He said the assault reminded him of scenes from the film Money Heist, the Spanish crime drama that follows robbers carrying out elaborate heists.
Video footage widely shared on social media showed people grabbing what appeared to be cash off the streets in the aftermath of the attack.
“It was pretty terrifying,” said Gustavo Inacio, 21, adding that the assault had been concentrated in the central parts of the city. “I couldn’t sleep out of fear that they would come to the other neighborhoods.”
Law enforcement officials said investigators from across Santa Catarina, neighboring states and the federal government had been mobilized to search for the gunmen.
“All the police forces in the state of Santa Catarina are working jointly to track down information and identify the perpetrators of this crime,” Paulo Koerich, the chief of the civil police in the state, said in a statement. “We will not tolerate these criminal actions in the state of Santa Catarina.”
Ernesto Londoño reported from Rio de Janeiro, Livia Albeck-Ripka from Melbourne, Australia, and Elian Peltier from London. Reporting was contributed by Mike Ives, Manuela Andreoni, Letícia Casado, Yan Zhuang and Daphné Anglès.