The Brazilian army has been deployed to the complexo da mare, a community made up of several shantytowns in Rio de Janeiro.
The move follows attacks on police that have resulted in the most tense standoff for years in the area.
The government says the show of force is necessary to keep the violence in the slums, known as favelas, from spiraling out of control.
Al Jazeera's Rob Reynolds reports from Rio de Janeiro.
Source: Al Jazeera