A police raid aimed at alleged drug traffickers that left at least 25 people dead in a shootout in a Rio de Janeiro slum has drawn criticism from the United Nations human rights office, which is calling for an independent investigation, citing a history of "disproportionate and unnecessary" use of force by police in Brazil.Helicopters and a contingent of some 200 heavily armed police officers on Thursday descended on the crowded, poor and mostly non-white community of Jacarezinho – one of the city's largest slums, which is largely controlled by one of the country's leading criminal gangs, Comando Vermelho, or Red Command. Witnesses described the operation as a terrifying firefight, with suspects leaping from rooftops."We call for the prosecutor to conduct an independent and thorough investigation into the case according to international standards," Rupert Colville, a spokesman for the U.N. High Commissioner for Human Rights, said Friday at a briefing in Geneva.He said Thursday's police operation "furthers a long-standing trend of unnecessary and disproportionate use of force by police in Brazil's poor, marginalized and predominantly Afro-Brazilian neighborhoods, known as favelas."The use of such force should only be a last resort, Colville said.Police say at least 24 drug traffickers and one police officer were killed in the raid. They have denied any wrongdoing and say they acted in self-defense. But residents of Jacarezinho say police gunned down suspects who wanted to surrender and barged into homes without a warrant. Two civilians were injured inside a subway when a stray bullet shattered the glass of a car, The Associated Press reported. Stray bullets also injured three police officers, according to the Rio Times.Felipe Curi, a detective in Rio's civil police, denied there had been 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," Felipe Curi, a detective in Rio's civil police, said during a news conference Thursday, according to the AP.Speaking to Reuters, police chief Ronaldo Oliviera described Thursday's raid as resulting in "one of the largest death tolls in a police operation in Rio." A similar police raid in Rio's northern outskirts killed 29 people in 2005.Last year, Brazil's Supreme Court banned police operations in favelas during the pandemic, except in exceptional circumstances. However, human rights groups say the ruling hasn't stopped authorities from using indiscriminate lethal force against some of the country's most vulnerable populations.Human Rights Watch says that in 2019, 6,357 were killed at the hands of police nationwide, nearly 80% of them Black. HRW says in the first half of 2020 police killings rose 6%. Police have reportedly killed more than 450 people in Rio de Janeiro state in the first three months of this year alone.The U.N. was joined by Amnesty International in condemning the raid."The number of people killed in this police operation is reprehensible," Jurema Werneck, executive director of Amnesty International Brazil, said in a statement. "The Rio de Janeiro state prosecutor's office must conduct a prompt, exhaustive, independent, and effective investigation into these atrocities, following international standards so that the agents of the state who ordered, committed or participated in this massacre are held accountable and face justice."NPR's Philip Reeves in Rio de Janeiro contributed to this report. Copyright 2021 NPR. To see more, visit https://www.npr.org.