A massive police operation against drug traffickers in a Rio de Janeiro favela Thursday left at least 24 suspects and a policeman dead, Brazilian media reports said.

The early-morning raid turned the impoverished neighbourhood of Jacarezinho, on Rio's north side, into a battlefield, with residents posting videos on social media of explosions, heavy gunfire and helicopters hovering overhead.

Large groups of police could be seen streaming into the favela as frightened residents tentatively went about their business once the gunfire died down, AFP correspondents said.

Residentes protest after a police operation against alleged drug traffickers at the Jacarezinho favela in Rio de Janeiro, Brazil, on May 06, 2021. Photo: AFP

At least two people were wounded when the subway car they were riding in was apparently caught in the crossfire during the operation, news site G1 reported, citing the police.

The sting targeted drug traffickers accused of recruiting minors, police said in a statement.

The neighbourhood is considered a base for the Comando Vermelho, or Red Command, the Brazilian beach city's biggest drug gang.

Rights group Instituto Fogo Cruzado (the Crossfire Institute) said it was the deadliest police operation in Rio since it began monitoring five years ago.

The operation came despite a Supreme Court ruling barring police from carrying out raids in Brazil's impoverished favelas during the coronavirus pandemic except in "absolutely exceptional circumstances."