A death squad has killed at least 30 people in the Brazilian state of Rio de Janeiro, police say.
Military police are suspected of being behind the killings
Several teenagers and a child were among those gunned down on Thursday night in towns in the districts of Queimados and Nova Iguacu.
Authorities say they are looking at the possible role of what they call rogue police, in a potential act of reprisal for recent arrests of eight officers.
Rights groups accuse police of carrying out a 1993 massacre in the state.
Twenty-one people were killed.
'Rain of gunfire'
Rio Public Security Secretary Marcelo Itagiba said he suspected the involvement of military police in Thursday's incident.
"The Security Secretariat is working with the hypothesis that this massacre was an act of reprisal for operation Navalha na Carne," he said.
Witnesses told reporters that the gunmen pulled up and opened fire, leaving victims no time to escape.
"It was very quick. I got up to my house and went down the hallway when I heard a rain of gunfire," Creuza Regina said.
In Nova Iguacu the attackers targeted a bar, in what Brazilian reports describe as a drive-by shooting.
Rio is one of the most violent cities in the world.
Rival drugs gangs are in control of many slum areas, known as favelas.