More than 1,000 Brazilian police and soldiers are searching Rio de Janeiro's largest slum for weapons and ammunition amid a crackdown on drug gangs.
In recent weeks, a series of intense shootouts led Brazilian authorities to ask the military for help patrolling the perimeter of Rocinha.
The press office of the police said there was one confrontation during Tuesday's operation, but it did not have additional details.
Rio, which has long struggled with crime, is experiencing its worst wave of violence in a decade amid a national economic crisis.
About 8,500 troops were deployed in August to curb violence a year after Rio hosted the Summer Olympics.