Brazil sent troops and tanks into poor neighborhoods to help reinforce police units whose battles this week against criminal gangs have left 23 dead, numerous buses and cars destroyed, and several schools closed.
According to a Folha de São Paulo report, authorities expect more violence and have intercepted phone conversations between criminal gangs in which the leaders talk of placing explosives in public places such as malls.
Brazilian authorities, speaking anonymously, blamed most of the attacks on Comando Vermelho, the powerful criminal syndicate that began in the country's prisons and now controls the distribution of drugs and weapons in numerous "favelas," the name given to poor neighborhoods in Brazilian cities.
Folha says the attacks are a response to the government's policy of placing special military police units known as the Pacific Police Units (UPP) in the "favelas," and the transfer of several top leaders of the criminal groups to more secure federal prisons.
The UPPs are part of the government's attempt to take control of the areas, as worries grow that the violence could affect the Olympic Games, which are to be held here in 2016.