RIO DE JANEIRO — More than 3,000 soldiers and military police officers moved into four big slums early Thursday seeking to arrest drug traffickers and hunt for the men suspected of gunning down a police inspector last week.

A military spokesman, Col. Roberto Itamar, said 3,000 soldiers were involved in the operation in Rio de Janeiro.

Military police also participated, though authorities did not say how many. Local media estimated there were 400. Brazil’s military police do traditional policing and are not part of the army.

Itamar said no gunfights had taken place during the operation.

The O Globo TV network broadcast images of people being taken into custody, but Rio’s Public Security Department did not immediately release any numbers on arrests.

Also on Thursday, Human Rights Watch said in its 2018 World Report that Brazilian authorities need to take decisive action to curb extrajudicial killings by police.

Maria Laura Canineu, Brazil director at Human Rights Watch, said at a news conference that Brazil’s police need “community cooperation to fight the high levels of crime that plague the country, but as long as some police officers beat and execute people with impunity, communities will not trust the police.”

The report said 437 Brazilian police officers were slain in 2016, most of them while off duty. It said police officers killed at least 4,224 people that year.