The four dead inmates were all believed to belong to the same gang faction and had fought side by side during Monday’s clash The confrontation involved members of the Comando Classe A gang, little known outside Para, and inmates from the rival Comando Vermelho, which hails from Rio de Janeiro SAO PAULO: Four inmates in northern Brazil were suffocated to death on Tuesday as they were being transported from a violent prison where 57 others were killed on Monday in an orgy of gang-related bloodletting, authorities said. Brazil has struggled for years to contain prison violence, amid a ballooning prison population that now ranks as the world’s third highest. Prisons are overcrowded and staffing is short, with rival gangs often vying for effective control of the facilities. Authorities in the northern state of Para said on Wednesday the four dead inmates were all believed to belong to the same gang faction and had fought side by side during the Monday clash, in which over a dozen were decapitated. The mass killing sparked widespread outrage in Brazil, and prison authorities said the violence had caught them by surprise with no intelligence suggesting an imminent confrontation, underscoring that prison violence is far from being controlled. As part of the response, state authorities in Para said they would move some of the prison’s most dangerous inmates to different facilities, in an attempt to alleviate overcrowding and prevent further violence. But it was during one such transfer, in a truck carrying 30 prisoners in four separate holding cells, that the four inmates were killed on Tuesday. Prison workers only found their bodies, all showing signs of suffocation as the cause of death, when the truck arrived at a new facility, Para’s State Secretary for Public Security and Social Defense, said in a statement. It gave no further details and state officials did not respond to follow up questions. The state said the matter is under investigation. Monday’s clash involved members of the Comando Classe A gang, little known outside Para, which set fire to a cell containing inmates from the rival Comando Vermelho, which hails from Rio de Janeiro and has expanded deep into northern Brazil. Brazil’s notorious gangs have been linked to bank heists, drug trafficking and gun-running, with jailed kingpins presiding over criminal empires via smuggled cellphones.