At least 18 people have been killed in a horror massacre in a Brazilian favela after 400 armed police raided the slum home to an organised crime group.
A local woman, an officer and 16 gang members were among the dead in Complexo do Alemao after the hours-long shootout which saw police helicopters trading fire with the targets after a dawn raid.
Officers were backed up by ten bulletproof vehicles and four helicopters as they tried to crack down on the criminal group that had robbed vehicles carrying cargo for banks and other businesses.
Videos circulating on social media showed intense shootouts between criminals as well as a police helicopter flying low over the small, brick houses, and barricades set on fire to prevent the passage of security forces.
Residents waved white towels and sheets in a signal to surrender but the slaughter continued, with locals carrying the bodies of the dead wrapped in blankets through the impoverished streets.
At the site of the raid, residents carried about 10 bodies as bystanders shouted, 'We want peace!'
'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.
Law enforcement authorities defended their officers' conduct during the operation, saying that units had been 'violently attacked' with 'military and guerrilla' tactics, while accusing the alleged gang members of using civilians as human shields.
Thursday's operation began before dawn and finished around 4 pm local time, police said. Nearly 400 police officers were involved, including Rio's tactical police unit, according to the police statement.
Ronaldo Oliveira, an investigator with Rio's police force, said officials would have rather just made arrests of suspects 'but unfortunately they chose to fire at our policemen.'
Police spokesman Ivan Blaz said the operation's goal was to stop the 'expansionist policy' of criminal gangs in Complexo do Alemao.
President Jair Bolsonaro lamented the death of the police officer, 38-year-old Bruno de Paula Costa, but did not mention any of the other people killed.
'He died after a clash with criminals,' the far-right leader said in a statement broadcast on social media.
Colonel Rogerio Lobasso, the officer in charge of the operation, expressed his condolences over the 50-year-old woman's death, which he said is under investigation.
Her boyfriend told news site G1 that police had shot her while they were stopped at a traffic light.
'They shot at the car. I just saw her collapse next to me. When I looked, she had a hole in her chest,' said Denilson Gloria.
Police often carry out raids in Rio's slums in a bid to fight organized crime and drug trafficking.