Rio de Janeiro - At least 10 people were killed in an hourlong gun battle with police in a Rio de Janeiro slum as officers were hunting for a stolen beer truck.

Police told Brazilian media that all the dead were criminals and the only casualty among law enforcement was an injured officer in Monday's operation in the town of Duque de Caxias in the Mangueirinha slum.

The shooting began when a police vehicle searching for the stolen truck was cornered in Duque de Caxias, and its officers called in reinforcements, media reports said, citing police. Dozens of officers responded and stormed the area with armoured cars and a helicopter.

Five people were arrested and weapons and drugs were seized, police said.

Residents of Duque de Caxias and relatives of those killed took to the streets Monday night to protest the police operation.

Violent police raids in Rio's "favelas," or slums, have become more frequent in recent months. Nine people were killed two weeks ago in a police operation in the Minha Deusa favela, and the total number of civilian deaths in such raids is 75 so far this year, according to police. The victims have included children and retirees.

The operations often resemble military battles, and human rights groups have criticized the police for failing to attend to the rights of poor residents. (dpa)