The deadliest police operation against drug gangs in Brazil's history killed at least 121 people, authorities said on Wednesday, as Rio de Janeiro residents lined a street with dozens of corpses found overnight.

State police said the raids targeting a major drug gang had been planned exhaustively for more than two months, and were designed to drive suspects into a forested hillside where a special operations unit was waiting in ambush.

"The elevated lethality of the operation was expected but not desired," Victor Santos, head of security for Rio state, told a news conference. He also promised an investigation into any police "misconduct".

Rio police confirmed 121 deaths so far, including four officers. Public defenders said the final count would rise to at least 132. President Luiz Inac

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