Residents of a Rio de Janeiro favela spent all night collecting bodies from inside the urban community, bringing them down in trucks and lining them up next to one another on a central square.

By early morning, at least 50 bodies of mostly topless, young men lay on the ground in Penha, one of the two sites targeted in Rio’s most lethal police operation ever on Tuesday.

They were surrounded by hundreds of locals, many of them crying and screaming.

Local activist Raull Santiago said he was part of a team that found around 15 bodies before dawn.

"I am at a loss for words to convey the significance, the gravity of what we have been witnessing since yesterday, into the early hours of this morning," said Santiago.

"I believe (it) will go down in history as one of the greatest massacres in our country," he added.

At least 64 people, including four police officers and 60 suspected criminals, were killed on Tuesday during a raid involving 2,500 police officers.

It is unclear whether the bodies were part of that total, but residents and activists said they were unlikely to have been tallied by the state government, as many were found in the surrounding green areas.

The United Nations' human rights body said Tuesday it was “horrified” by the deadly police operation, called for effective investigations and reminded authorities of their obligations under international human rights law.

Rio has been the scene of lethal police raids for decades.

In March 2005, some 29 people were killed in Rio’s Baixada Fluminense region, while in May 2021, 28 were killed in the Jacarezinho favela.

AP vide by Lucas Dumphreys