A police car screeched to a halt in the Novo Mundo slum. Children scattered as three officers with guns and bulletproof vests leapt out and ran into a tenement. Minutes later, the police left and an angry 17-year-old emerged, presenting bruises on his cheek and chest as evidence of the officers' abuse.

"I have no idea why they did this," Diego Romao dos Santos muttered as he walked down the dusty streets.

In Novo Mundo and other "favelas" that surround Brazil's largest city, police are more feared than gangs, and anger over police brutality helped fuel a week of attacks that has killed at least 170 people.

The violence erupted in the 600 overcrowded and crime-infested favelas sprinkled around Sao Paulo, a city of 18 million. Jailed leaders of the First Capital Command, or PCC, Brazil's most notorious organized crime group, lashed out after police transferred them to a remote prison. Using cell phones smuggled into their cells, they commanded their "soldiers" to strike back at the state.

CountryWatch: Brazil

Slum dwellers attacked courthouses, banks and police stations with machine guns, grenades and Molotov cocktails. They set buses on fire and seized control of prisons.

Gunbattles rang out in the streets and public transportation ground to a halt. Businesses in Brazil's financial capital closed, and frightened parents kept children home from school.

By Friday, when the violence appeared to subside, authorities had counted 170 dead — 107 suspected criminals, 41 police and prison officers, 18 inmates and four civilians.

For Cicero Pinheiro de Nascimento, president of the Novo Mundo Residents' Association, nobody should have been surprised by the PCC's ability to mobilize in the slums. Police raids like the one Thursday in which the teenager was roughed up are a common occurrence, he said.

"What you saw has been part of our daily lives for years," Nascimento said, walking along an open-air sewer surrounded by wood-and-cardboard shacks housing some of Novo Mundo's 12,000 residents.

"We are the weakest link in a society that sees us as criminals and treats us as the scum of the Earth," he said. "We are easy prey for corrupt police who abuse their power and demand money in exchange for not taking us to jail on trumped-up charges of drug or weapons possession."

Throughout the week, human rights groups have questioned the police backlash as officials refused to give details of the rising death toll among "suspected criminals." Asked Friday about allegations of police brutality, the Sao Paulo state police had no immediate comment.

Unlike other Latin American crime gangs with international ties, the PCC is confined to Brazil, and runs its operations — drug and weapons smuggling, bank holdups, kidnappings, extortion and murder — chiefly from the slums of Sao Paulo.

Most favela residents are not enamored of the PCC, but they often look the other way, finding the gang less threatening than the law.

"You don't mess with (the PCC), and they won't mess with you," Nascimento said. "If you do mess with them, they will kill you. But they do not cause the fear and hatred slum dwellers feel toward police."

Across town in the Nelson Cruz slum, a labyrinth of narrow, dark and dank alleyways, one woman said the PCC wins support by protecting residents from "other bandits who once in a while try to rob us." But she said residents are fearful of the gang as well, and asked that her name not be used "because they may come after me if they knew I talked to you."

"One can survive here only by not getting involved with them," she said.

But each time police sweep through her shantytown, the PCC gains supporters, she said. "I know too many people who have been victims of police abuse to trust those who are supposed to protect me."

In a report last year, Amnesty International said police brutality had turned slum dwellers against authorities across Brazil.

"Persistent abuse and violence by elements within the police have created a culture of fear and revulsion within the favelas," the human rights group wrote, adding that disenfranchised youth tend to see drug dealing and other crimes as their only option.

Often slum dwellers view police as corrupt and violent and gang leaders as "successful role models," according to Folha de Sao Paulo newspaper columnist Gilbert Dimenstein. Until poor youths have more opportunities, he wrote, the slums will remain recruiting grounds for organized crime.

Residents of Novo Mundo agreed.

"I know many kids as young as 12 who are already dealing in drugs and who dream of joining the PCC," said Normelia Silva Santana, who earns a living selling recyclable trash.

She glanced at her 14-year-old son, Sandro.

"Luckily he is not one of them," she said. "He knows that to survive here, he has to hide from the police and not mess around with the gangs."