Brazilian police have been accused of killing innocent people during a huge operation this week against drug gangs in a Rio de Janeiro shanty town.
Police have been operating in and around the slum since May
Police battled traffickers on Wednesday in the Alemao slum, killing 19 people.
Families and human rights group say the police action was excessive but Rio officials insist those killed were involved in drug-trafficking.
Rio's state security chief said there would be more operations to tackle the gangs that rule many of Rio's slums.
The human rights commission of the Brazilian lawyer's association said it had received complaints that innocent people were among those killed during the fierce fighting that erupted on Wednesday.
Residents say three youths under 16 years of age were among those killed.
Rio authorities say more shanty towns will be targeted
"We believe the residents and we are going to take legal action against the authorities," Joao Tancredo from the lawyers association said during a visit to the Complexo do Alemao or German Complex slum.
The slum, home to some 100,000 people, had been targeted by police since the start of May but Wednesday's raid was the biggest and bloodiest offensive to date.
More than 1,000 heavily armed police and special forces went in, backed by armoured vehicles and helicopters.
The authorities have insisted their actions were justified to tackle the powerful drug gangs who control about half of Rio's 750 shanty towns.
Rio de Janeiro officials are also trying to make the city safer before it hosts the Pan-American games on 13 July.
Some 5,500 athletes and about 800,000 tourists are expected to visit the city for the games.
The city is also one of the host venues for the global series of Live Earth rock concerts on 7 July.
Rio's state security secretary Jose Mariano Beltrame said the police operation in the German Complex was only the first of many to be carried out in the shanty towns.
"Police don't have the resources to intervene in every one of Rio's slums. That's why we decided...to start with the German Complex where the crime rate is extremely high," Mr Beltrame said.
"But we will conduct operations in other shanty towns; when and where will depend upon police intelligence."
The Alemao slum was calmer by Thursday but Rio Police Chief Gilberto Ribeiro said there could be further operations to disarm the drug gangs there.
Community leaders expressed concern that there could be more police action.
"For the police, everyone is a drug trafficker, especially after they have killed you," Edmundo Santos Oliveira told the Associated Press. "Then it is up to the family to try to prove their loved ones were innocent."