Sao Paulo, Brazil (CNN) -- Rio de Janeiro's special police forces declared Sunday that they were in full control of one of the city's biggest and most notorious shantytowns, Rocinha, after a predawn operation aimed at wresting control from drug traffickers. The operation, involving 3,000 police and security forces, had successfully occupied Rocinha and neighboring slums Vidigal and Chacara do Ceu, the Rio de Janeiro government said on its website. "The next stage will be looking for the criminals that were able to get out of the places we are working," military police Col. Alberto Pinheiro Neto told reporters Sunday morning.
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NEW: A former police inspector says the operation will cut down on Rio's drug supply
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Governor: "We are rescuing communities that were abandoned for decades"
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Rio de Janeiro is trying to crack down on crime before the 2014 World Cup
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Steep roads in Rocinha are covered in oil, possibly in an attempt to hinder police
Police arrested @placeholder's top suspected drug trafficker days before they moved in.