Sao Paulo , Brazil ( CNN ) -- Tanks , troops and police pushed through the streets of two shantytowns in northern Rio de Janeiro Sunday in a move to retake control of some of the city 's most crime-ridden areas . In the predawn operation , state authorities targeted the slums , or favelas , of Jacarezinho and Manguinhos with more than 2,000 military troops and police . They have a larger long-term goal : securing 40 slums before the World Cup in 2014 , and keeping them safe for the Olympics two years later . Police said they seized automatic weapons , guns and grenades and arrested dozens of people in a series of slum raids over the weekend . There were no reports of deaths or injuries Sunday . On Saturday , police said five suspected drug dealers were killed during a slum raid . Police have already taken over about 30 favelas since they began operations in 2008 , but it 's an uphill battle . About one-fifth of Rio 's residents live in the city 's 1,000 shantytowns , many of them perched on steep hills overlooking beachside condominiums . Jacarezinho and Manguinhos are smaller favelas , far from tourist hotspots , but they became centers for organized crime and drug dealing after other slums were taken over by police . Sunday 's operation there stands in stark contrast to the invasion of the Alemao favela in 2010 , when more than 30 people were killed in shootouts . Police now announce days in advance when they 're going to go into a community , to avoid major violence . But critics say it simply gives criminals a chance to escape to another slum , or the suburbs . Authorities said they planned to set up a `` police pacification unit '' in Manguinhos by December , and in Jacarezinho by January . Three years ago , they took a similar approach in the notorious Cidade de Deus , or City of God , slum where military police backed by the army seized control from drug traffickers . `` They were abandoned for 40 , 50 years , '' said Maj. Bruno Xavier of the police pacification unit there . `` You ca n't recover that in three years . '' But now , Xavier told CNN last month , they plan to prove to the slum 's 40,000 residents that they 're here to stay .
Two slums are targeted in an operation aimed at cleaning up crime before the World Cup . More than 500 police and soldiers march through the streets of both towns . There are no reports of hundreds of injuries .