At least nine people have died in gun battles with drug dealers in a favela (shanty town) in the Brazilian city of Rio de Janeiro, police say.
The clashes started on Monday evening after a demonstration in Bonsucesso, which reportedly ended in mass robberies near Rio's main access road.
Hundreds of police and National Guard officers, with the support of a tank, are being deployed to secure the area.
Police say at least six of the victims were suspects and one was a policeman.
At least nine others were arrested during the operation in the Favela da Mare area, and a number of guns and drugs were confiscated, police say.
The violence broke out on Monday evening, after a peaceful demonstration ended in mass robberies.
Shops, passers-by and demonstrators were robbed by a group of criminals, police say.
The gang went on to shortly block one lane of Avenida Brasil, Rio's main access road, before running into Favela da Mare, police say.
The clashes took place as police followed the group into the favela.
A man who was returning home was shot in the head, according to local reports.
A police officer and another seven civilians also died in the clashes.
Local schools remained shut on Tuesday, affecting thousands of children.
The Mare area comprises a series of interlinked shanty towns which are home to more than 130,000 people.
Rio de Janeiro's pacification programme, which promotes occupation of shanty towns to push out drug trafficking gangs, has not yet reached the area.
Earlier this year, police occupied the neighbouring favelas of Complexo do Caju and Barreira do Vasco without trouble.