RIO DE JANEIRO (AP) — On Tuesday, police in Rio de Janeiro launched an operation in two of the city’s favelas that left 121 dead, including four police officers, and an unknown number of people wounded.

Brazil’s public defender’s reported 132 deaths in the raid, more than the official police numbers. Police and soldiers launched the raid supported by helicopters, armored vehicles and ground troops, targeting the Comando Vermelho, or Red Command, gang.

Here are some things to know about criminal activity and the large-scale police raids as a strategy to fight gangs:

The origin and rise of Comando Vermelho

The Comando Vermelho, known as Red Command, originated in the late 1970s inside a Rio de Janeiro prison, where common criminals and political prisoners from Brazil’s military dictators

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