Drug-fueled crime has wracked Rio's slums for many years. The city has struggled to contain the violence – local militias have even been formed in some neighbourhoods to fight gangsters.
People protested against violent crimes at
Rio's Copacabana beach on Saturday [AP]
But in recent months a series of brutal attacks – including the murders of a six-year-old child and three French NGO workers – have pushed the issue out of the slums.
Ignacio Cano, a sociologist at the State University of Rio, said: "This represents really a serious crisis in terms of public security in Brazil, and in particular main cities like Rio de Janeiro."
Cariocas – as Rio residents are known – are outraged. On Saturday almost a thousand people lay down on the famous Copacabana beach to symbolise the hundreds of people killed in recent months.
If the president decides to send in the troops, it would not be the first time that soldiers have been called in to deal with urban security.
They have helped protect summits and will provide security for the Panam games that Rio will host in July.
But Cano said that while "most people do feel that the situation is very serious … not everybody agrees that calling in the army is the best solution".
Gang broken up
Meanwhile, Brazilian police said they had broken up a gang that carried out nearly a thousand contract killings over the past five years.
The gang based in Pernambuco state included policemen, hired guns and businessmen and also dealt in drugs and gun trafficking.
A police superintendent described the ring as a kind of "Homicide Incorporated".
They charged $500 to $2,500 for each killing.
Eighteen suspects were arrested and police are looking for 10 more.