About 60 people were killed in a bloody prison riot in the Amazon jungle city of Manaus sparked by a war between rival drug gangs, officials said on Monday , in the worst violence in over two decades in Brazil’s overcrowded penitentiary system. The head of security for Amazonas state, Sergio Fontes, told a news conference that the death toll could rise as authorities get a clearer idea of the scale of the rebellion sparked by a fight between rival drug gangs.