At least 24 criminals were killed in a shootout with police in a Rio de Janeiro slum.

Authorities claim the police mission killed two dozen criminals but residents and activists claimed there were human rights abuses.

Dozens of officers from Rio de Janeiro state’s civil police stormed Jacarezinho, a favela in the city’s northern zone. They were targeting drug traffickers from one of Brazil’s most notorious criminal organisations, Comando Vermelho, and the bodies piled up quickly.

When the fighting stopped, there were 25 dead – one police officer and 24 people described by the police as “criminals”.

Rio’s moniker of ‘Marvellous City’ can often seem a cruel irony in the favelas, given their stark poverty, violent crime and subjugation to drug traffickers or militias. But even here, Thursday’s clash was a jarring anomaly that analysts declared one of the city’s deadliest police operations ever.

The bloodshed also laid bare Brazil’s perennial divide over whether, as a common local saying goes, “a good criminal is a dead criminal”. Fervent law-and-order sentiment fuelled the successful presidential run in 2018 by Jair Bolsonaro, a former army captain whose home is in Rio. He drew support from much of society with his calls to diminish legal constraints on officers’ use of lethal force against criminals.

The administration of Rio state’s Governor Cláudio Castro, a Bolsonaro ally, said in an emailed statement that it lamented the deaths, but that the operation was “oriented by long and detailed investigative and intelligence work that took months”.

The raid sought to rout gang recruitment of teenagers, police said in an earlier statement, which also cited Comando Vermelho’s “warlike structure of soldiers equipped with rifles, grenades, bulletproof vests”.

Television images showed a police helicopter flying low over the Jacarezinho favela as men with high-powered rifles hopped from roof to roof to evade officers.

Others didn’t escape.

One resident said a man barged into her home around 8am bleeding from a gunshot wound. He hid in her daughter’s room, but police came rushing in right behind him.

She said that she and her family saw officers shoot the unarmed man.

Hours later, his blood was still pooled on her tiled floor and soaked into a blanket decorated with hearts.

Yesterday, protesters gathered outside police headquarters near Jacarezinho to denounce the violence, holding a banner that read “STOP KILLING US!”

Even shortly after the shooting died down, about 50 residents of Jacarezinho poured into a narrow street to follow members of the state legislature’s human rights commission who were conducting an inspection. They shouted “Justice!” while clapping their hands. Some raised their right fists into the air.

Felipe Curi, a detective in Rio’s civil police, denied there were any executions.

“There were no suspects killed. They were all traffickers or criminals who tried to take the lives of our police officers and there was no other alternative,” he said at a news conference.

Mr Curi said some suspects had sought refuge in residents’ homes, and six of them were arrested. Police also seized 16 pistols, six rifles, a submachine gun, 12 grenades and a shotgun, he said.