RIO DE JANEIRO — Police searched homes and secured the perimeter of a Rio de Janeiro shantytown Friday that has long been a stronghold for drug gangs and a symbol of the their ability to rule vast areas of the seaside city with impunity.

About 80 federal police officers joined state police in door-to-door searches in the Vila Cruzeiro slum as 800 military troops, trained in surrounding and isolating conflict areas, stood ready to back them up. The area had been taken by law enforcement just hours before during a five-hour operation using armored vehicles and assault rifles.

Slum residents, streaming out down steep, narrow alleys to jobs in the city below, had mixed reactions as officers approached them. Some ran away, and others stayed to welcome and cooperate by showing their identification.

More than 80 abandoned motorcycles and at least one body were found during the search this morning, reminders of the gang’s quick retreat the day before to the neighboring Alemao complex of shantytowns — among the best defended gang turf in the city.

About 192 people have been arrested or detained since the start of the widespread violence allegedly instigated by criminals since Sunday, according to a police spokesman. More than 96 buses and cars have been burned on major roadways, many motorists have been robbed and police outposts have been shot in the city that will host the final match of the 2014 World Cup as well as the 2016 Olympics.

It is unclear how many people died in Thursday’s violence, but police said at least 25 have died since Sunday.

The military support was authorized late Thursday by the president to help police keep their hold on the occupied area.

“Anything we can do for Rio, we’ll do,” President Luiz Inacio Lula da Silva told reporters from Guyana, where he is attending a summit of the Union of South American Nations.