Elite police units backed by armoured military vehicles and helicopters invaded Rio de Janeiro's largest slum of Rocinha, in the most ambitious operation yet in an offensive that seeks to bring security to a seaside city long known for violence.
The action at dawn on Sunday is part of a policing campaign to drive heavily armed drug gangs out of the city's slums, where the traffickers have ruled for decades.
"This is significant because this is one of the most biggest shanty towns and this is part of a big operation," Al Jazeera's Gabriel Elizondo reporting from Rio de Janeiro said.
"Good news is that so far we have not heard any gun fire" and that is "probably by the fact that the police have arrested one of top traffickers in the last three days who ran this favela," he added
Authorities vow to continue the crackdown and stabilise Rio de Janeiro's security before it hosts the 2014 World Cup and the 2016 Olympics. Officials are counting on those events to signal Brazil's arrival as a global economic, political and cultural power.
"Rocinha is one of the most strategically important points for police to control in Rio de Janeiro," said Paulo Storani, a security consultant and former captain in the elite police unit leading the invasion.
Al Jazeera's Gabriel Elizondo reports live from Rio de Janeiro
"The pacification of Rocinha means that authorities have closed a security loop around the areas that will host most of the Olympic and World Cup activities."
The Rocinha slum is home to about 100,000 people living in flimsy shacks that sprawl over a mountainside separating some of Rio de Janeiro's richest neighbourhoods. The location has made it one of the most lucrative and largest drug distribution points in the city.
"This action is a huge blow to the structure of drug trafficking in Rio de Janeiro and against the second-largest drug faction,'' Storani said. "Beyond that, it's essential to have security in this area simply because of the huge number of people who circulate there.''
The invasion of Rocinha comes near the end of a watershed year in the fight against drug gangs that rule more than half of Rio de Janeiro's 1,000 slums, where about one-third of the city's 6 million residents live.
"You can't over estimate how important this is ... because this is an area that the state and police could never go into permanently it was completely run by drug traffickers for decades now," Elizondo said.