The Brazilian army carried out an operation on Saturday in four favelas (shantytowns) of Rio de Janeiro, including Rocinha, the largest in the country, Xinhua reported.
According to the Eastern Military Command, over 1,000 soldiers took part in the simultaneous operation in the favelas of Rocinha, Vidigal, Chacara do Ceu and Parque da Cidade, all four located in the southern part of the city.
The military organism said four people were arrested.
Local media reported that the operation sparked intense firefights in the favelas, especially Rocinha, which forced the army to stop traffic on the highway that connects the west and south of Rio, running next to the favela.
The army statement said the operation saw soldiers surround the favelas and remove barricades erected by drug trafficking and criminals.
Saturday's operation marked the first time the army had entered Rocinha since President Michel Temer declared a federal security takeover of Rio in February, to end the wave of violence in the region.
The operation happened after a shootout between security forces and criminals on Friday forced the cable car to the Sugarloaf Mountain, one of Rio's main tourist attractions, to temporarily suspend operations.