At least twenty-five people have been killed in a shootout between suspected drug traffickers and police in the Brazilian state of Rio de Janeiro.

Rio police said the gunbattle took place on Thursday, describing the clash as one of the state’s deadliest police raids.

People targeted in the raid in the poor Jacarezinho neighborhood tried to escape across rooftops as police arrived in armored vehicles, and helicopters flew overhead, television images showed.

The firefight forced residents to shelter in their homes.

The victims included one police officer, and the remainder were suspected members of the drug-trafficking gang that dominated life in the slum, including some of its leaders, Reuters reported one Rio police official as saying.

The bloodbath prompted criticism from human rights groups including Amnesty International, who condemned the police for the “reprehensible and unjustifiable” loss of life in a neighborhood mostly populated by Black and poor people.

Human Rights Watch called on Rio state authorities to investigate and prosecute numerous cases of rights abuse against the police, adding that a thorough and independent probe into Thursday’s deaths was essential.

“This is one of the largest death tolls in a police operation in Rio, surpassing 19 at Complexo do Alemão slum in 2007, except we did not lose one of ours then,” police chief Ronaldo Oliveira said, referring to the bloody raid.

Thursday’s incident was the deadliest single police operation in sixteen years in Rio state which has suffered for decades from drug-related violence in its numerous favelas.

In 2005, a police raid in the Baixada Fluminense in Rio’s violent northern outskirts killed twenty-nine people.