Brazilian police backed by troops, helicopters and armoured vehicles have moved into shanty-towns near Rio de Janeiro's international airport.
More than 1,300 security personnel were involved in the operation in the Caju and Barreira do Vasco neighbourhoods.
It is part of a strategy to take control of Rio's poor districts from drug-trafficking gangs before next year's World Cup and the 2016 Olympics.
Security forces met no resistance as they moved into the area before dawn.
"The operation has been a a success, this important area was taken without firing a shot," military police Col Frederico Caldas told Brazil's Globo TV.
Three hours after they moved in, police hoisted the flags of Brazil and Rio to show the authorities were now in control of the neighbourhoods, after decades of domination by drugs gangs.
A number of arrests were made and guns and drugs seized.
The occupation of the shanty towns or favelas is part of a plan to secure access to and from Rio's international airport.
Since 2008 more than 30 favelas in Rio have been "pacified" in the government campaign to improve public security before it hosts the world's two biggest sporting events.
The programme has helped bring down crime rates in and around the communities, the BBC's Julia Carneiro in Rio says.
But there are more than 600 favelas in the city, and critics say the pacification programme only benefits areas near richer neighbourhoods popular with tourists or Olympic and World Cup venues, our correspondent adds.