Police in the Brazilian city of Rio de Janeiro have intensified a crackdown on drug gangs in the city's sprawling shantytowns, that has resulted in the death of at least 45 people and the detention of 192 others since the operation began last week.
Amid intermittent gunfire, security forces on Saturday were preparing to enter Alemao, another major shantytown or "favela" in the city's north, a day after troops entered Vila Cruzeiro, a neighbouring slum.
Soldiers in camouflage, black-clad police from elite units and regular police held their ground at the entrances to Alemao, a grouping of a dozen slums that climb up small slopes where more than 85,000 people live, according to the Brazilian government.
Al Jazeera's Gabriel Elizondo, reporting from Rio de Janeiro, said that it will not be possible to bring tanks into the Alemao favela. "This complex sits on hills, so the security forces will have to go in and engage in hand-to-hand combat," he said.
The standoff comes after a week of intense and widespread violence in the city, during which dozens of motorists were robbed and more than 100 cars and buses were set ablaze.
Authorities say the gangs are protesting against a two-year-old police campaign that has pushed the criminals out of slums where they have long ruled with impunity.
Brazilians have been glued to the continuous coverage of the violence on local television, which has shown buses engulfed in flames and elite police units battling their way through the slums.
Scores of men with packs and automatic rifles were seen scrambling up the hills beyond the slum, with many escaping in cars and on motorcycles.
Many had come to the Vila Cruzeiro slum to escape fighting in nearby districts, and it was not immediately clear whether the police had defeated the gangs or merely sent them scattering off to other areas fight.
"We've taken an important step, but nothing's been won," Jose Beltrame, the Rio state security chief, said.
"It's important to arrest people, to gather up drugs and ammunition, but it's more important to get them out of the territory," he said, referring to the drug traffickers that rule many of Rio's largest slums.
But Marcelo Freixo, a state deputy from Rio and longtime critic of local police tactics, said the operation would accomplish little.
"The police can enter Vila Cruzeiro and kill another hundred, but that won't solve the problem in Rio de Janeiro," he told the AFP news agency.
"The finger that pulls the trigger is not the same as the one that counts the money from arms smuggling, and in that sense the government appears to be concerned with only one of them."
Around two million of Rio's inhabitants – a third of the population – live in more than 1,000 slums, locally known as "favelas".
Authorities hope to pacify 100 of the most violent ones by 2014.
In October 2009 drug gangs shot down a police helicopter near the Maracana stadium – one of the main sites of the upcoming World Cup – killing three officers.
Al Jazeera and agencies.