By Gary Duffy
BBC News, Sao Paulo
Nineteen people have been killed in gun battles between rival drug gangs and in a separate incident involving police in Brazil's city of Rio de Janeiro.
Rio's police say they have also made several arrests
The battles are said to have involved drug dealers trying to gain control in the Morro da Mineira shantytown.
The shootings caused chaos in the central district of the city.
They happened as the government considers a request from Rio's governor for troops to be sent to the city to help police.
Earlier this year, a group of federal police officers were sent to Rio after an outbreak of violence, and more are due to go later this year to help provide security for the Pan-American Games.
The gun battle for the control of the Morro da Mineira caused chaos in Rio, with some of the drug dealers taking refuge at one stage in a nearby cemetery where a number of funerals were taking place.
Local TV showed families running to escape, and one man is said to have been seriously wounded while sitting on a bus.
Police say it was after the shooting they recovered the bodies of at least 13 suspected drug dealers.
Police say they have made several arrests and seized weapons, including grenades.
In the second incident, police say they shot dead six suspected drug dealers in a car in another part of the city and recovered 3,000 bags of cocaine.