( CNN ) -- Hundreds of military police raided a slum in northern Rio de Janeiro this weekend , seizing dozens of vehicles and hundreds of bundles of marijuana , state-run media reported Sunday . There were no exchanges of gunfire in the operation , the city 's public security chief Jose Mariano Beltrame told reporters on Sunday , according to Agencia Brasil . The peaceful operation is in stark contrast to what happened in Rio in November , when at least 35 people died in violence set off after drug gangs lashed out at the increased police presence in the crime-ridden slums , which are known as favelas , police said . That unrest led to a massive sweep of the Alemao favela complex that involved about 2,600 police and soldiers . This weekend 's operation , which culminated with the raising of a Brazilian flag Sunday morning in the Caixa d'Agua section of the city , was conducted by about 750 military police personnel . Brazilian intelligence agents and marines also played a role , with 14 armored vehicles , five helicopters and GPS units all used as part of the operation , Agencia Brasil reported . About 315,000 residents live in the affected neighborhoods , which include Morro da Mangueira , Morro dos Telegrafos and Candelaria . Authorities announced that they 'd seized 32 vehicles and 300 packs of marijuana . They 'd also served 55 arrest warrants issued in the preceding two months , with three arrested as part of the weekend operation . Beltrame defended the decision to give advance notice of the raid , saying it minimized the prospect of violence . He added that authorities have information on drug traffickers who fled the area ahead of the operation , saying they will be arrested when the time is right . While Brazil has made significant economic inroads in recent years , poverty and crime remain significant problems in several areas , particularly slums in cities such as Rio de Janeiro . That coastal city is among those that will play host to soccer 's 2014 World Cup , and two years later it will be home to the summer Olympics . CNN 's Marilia Brochetto contributed to this report .
There are no exchanges of gunfire , an official says , in contrast with late last year . Authorities arrested 3 and seized 32 vehicles and 300 bundles of marijuana . Rio de Janeiro is a host city for the 2014 World Cup and the 2016 summer Olympics .