A police raid on a favela near Rio de Janeiro Thursday left at least 13 people dead, including the suspected leader of a crime gang active in the north of Brazil, local media reported.

"There are 13 dead, two individuals detained and a large number of weapons seized," Fabricio Oliveira, from the Coordination of Special Resources of the Civil Police of Rio de Janeiro, told a press conference.

Police said the violence hit the Salgueiro Complex in the city of Sao Goncalo, part of the Rio metropolitan region.

The objective of the raid was "the capture of members of the Comando Vermelho (gang) from the (northern) state of Para who took refuge in the district," a police statement said.

Comando Vermelho is one of the oldest and largest crime gangs in Brazil, focusing heavily on drug trafficking.

Upon arriving in the favela, "police were attacked by criminals," leading to "an intense firefight," civil police said.

The governor of Para state, Helder Barbalho, said on Twitter that "Leonardo Araujo, known as 'L41,' fugitive, died in a clash with security agents. He was the main leader of the biggest crime organization that operates in Para and that also ordered various attacks in RJ," or Rio de Janeiro.

And Rio state governor Claudio Castro tweeted that "two criminals who controlled criminal gangs in (the northeastern state of) Sergipe and Para were captured," referencing Thursday's arrest and another operation in the northern part of the city.

According to police, Thursday's operation specifically targeted individuals responsible for a series of attacks against public security agents in Para, in which 40 officers have been killed since 2021.

It was also launched to target gang leaders "involved in recent attacks" in the western part of Rio, where several cars had been set on fire Wednesday.

Amnesty International Brazil slammed the Rio government, saying its actions were "disastrously lethal" and part of an "institutionalization of the policy of extermination" in the Sao Goncalo area.

"How long does the black, marginalized population of the favelas have to withstand the policy of war that drives police in Rio?" the NGO tweeted.

More than 1,300 people were killed at the hands of police in Rio de Janeiro state in 2021, according to the Violence Monitor data project.