Residents of Sao Paulo's slums are divided. "It's a relief, it's very quiet now," said an older woman on her way to work.

But another woman carrying her baby said: "Now that it's full of police, I get very scared. I get worried about a shootout or confrontation."

Many argue that when the police leave, things will revert to the brutal status quo unless far-reaching community projects are introduced to improve public access to services like schools and hospital.

"It's not just a question of sending in police," said Joildo Santos, a spokesman for the Paraisopolis Residents Association. "You have to have public works that give young people opportunities, alternatives."