"It could be 24 hours, over the weekend, three days, 15 days. The goal, as always, is the one we said before, to block organized crime, to create a surprise effect."
The second phase of a major military operation, across several favelas in Rio de Janeiro, has taken place on the first anniversary of the 2016 Olympic Games.
More than 1,300 police and 3,600 troops stormed five of the city's shanty towns, Rio's security chief Robert Sa said in a statement.
Twenty-four adults and two teenagers were reportedly arrested during the raid.
The security forces' goal was to detain gangs members thought to be responsible for a surge in robberies of commercial trucks; arrest warrants were issued for 40 people.
"We are going to stay in place until the goals are met," Defence Minister Raul Jungmann said in an interview with Globo. "It could be 24 hours, over the weekend, three days, 15 days. The goal, as always, is the one we said before, to block organized crime, to create a surprise effect."
In 2015, more than 3,300 out of the over 58,000 violent deaths recorded were the result of police intervention, according to the non-governmental organization Brazilian Forum of Public Security.
This corresponds to nine people killed every day by the Brazilian police.
The troops, armed with camouflaged personnel carriers, were part of 8,500 deployed to the city last month.
In Lins favela, soldiers took positions at every crossroads and outside many alleyways.
Units of members of the army and SWAT police also roamed the streets in open Jeeps and SUVs, with their weapons projecting from the windows of the vehicles.
Everyone entering or leaving the favela in northern Rio was subjected to an identity check and search.
"There's an atmosphere of tension and fear," said Vanuza Barroso da Silva, 23, who was leaving for her job at a supermarket.
"They treat us as if we're trash," her father Roberto, 46, said after going through the search.
Officials said the other favelas targeted were Camarista Meier, Morros de Sao Joao and Engenho Novo in the north, and Covanca in the west.