A police operation Thursday targeting gang members in Rio de Janeiro's largest complex of favelas, or low-income communities, left at least 18 people dead in one of the deadliest raids the city has seen recently and one already bringing more criticism of police violence.

Rio authorities said 16 suspected criminals were killed in confrontations with police in Complexo do Alemao along with a police officer and an woman. A police spokesman said the raid targeted a criminal group that stole cars and robbed banks, and invaded nearby neighborhoods.

Videos circulating on social media showed intense shootouts between criminals as well as a police helicopter flying low over the small, brick houses. Rio’s police have used helicopters to shoot at targets, even in densely populated residential areas, and video showed shots being fired from the favela at the aircraft.

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At the site of the raid, Associated Press reporters saw residents carrying about 10 bodies as bystanders shouted, “We want peace!” Residents said those who attempted to help the injured risked arrest.

“It’s a massacre inside, which police are calling an operation,” one woman told AP, speaking on the condition of anonymity because she feared reprisals from authorities. ”They’re not letting us help (victims),” she added, saying she saw one man arrested for attempting to do so.

A Rio’s police force spokesman said some of the criminals wore uniforms to disguise themselves as police officers.

“I would rather they (the suspects) had not reacted and then we could have arrested 15, 14 of them. But unfortunately they chose to fire at our policemen,” said Ronaldo Oliveira, an investigator of Rio’s police.

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Rio state Gov. Cláudio Castro said on Twitter he lamented the police officer's death.

"I will continue to fight crime with all my strength. We will not back down from the mission of guaranteeing peace and security to the people of our state,” Castro said.

But many disagree with the government's strategy for tackling violence and organized crime, an approach that regularly sees deadly police operations. A raid in Rio's Vila Cruzeiro favela in May killed more than 20 people.

Thursday's operation was aimed at locating and arresting criminal leaders, some from other states, police said in an early statement.

“ENOUGH of this genocidal policy, governor!” Talíria Petrone, a federal lawmaker for Rio, said in response to the governor's tweet. “This failed public security policy leaves residents and police on the ground, en masse. It’s no longer possible to keep piling up Black bodies and favela residents every day!”

Alemao is a complex of 13 favelas in northern Rio, home to about 70,000 people. Nearly three-quarters of them are Afro-Brazilians, according to a July 2020 study published by the Brazilian Institute of Social and Economical Analyses.

Earlier this year, Brazil’s Supreme Court established a series of conditions for police to conduct raids in Rio’s favelas as a means to reduce police killings and violations of human rights. The court ordered that lethal force be used only in situations in which all other means have been exhausted and when necessary to protect life.

The ruling came in response to a raid on the Jacarezinho favela in 2021 that resulted in 28 people being killed. As was the case Thursday, an officer died during that raid, which some speculated at the time was the cause for subsequent abuse and summary executions.

Thursday’s operation began before dawn and finished around 4 p.m. local time, police said. Nearly 400 police officers were involved, including Rio’s tactical police unit, backed up by four helicopters and 10 bullet-proofed vehicles, according to the police statement.

In a video shared by Voz da Comunidade, a community news outlet focused on Rio’s favelas, residents can be seen calling for peace and waving white cloths from their windows and rooftops.

Fabrício Oliveira, one of the coordinators of the police raid, said authorities fear that Friday could be another violent day at the Complexo do Alemao.

“Our experience has told us that after raids like these police are attacked in every way,” Oliveira said.