At least 18 people died on Thursday during a major police raid in a dense warren of Rio de Janeiro slums, state military police said, in the latest bloody confrontation in Brazil's second-largest city.

Tactical teams from Rio de Janeiro's civil and military police raided the Alemao complex to take down an alleged criminal organization. The group was suspected of involvement in cargo theft and bank robberies and was planning incursions into rival slums, the military police said in a statement.

At least 18 people died in the raid: one police officer, 16 alleged criminals and a female bystander, police said. The operation involved around 400 officers, four aircraft and 10 armored vehicles.