At least 13 inmates were killed and some 30 injured in a clash between rival gangs Oct. 10 at Pedrinhas prison in São Luis, in Brazil's northeastern state of Maranhão. Authorities said violence broke out after guards discovered inmates digging an escape tunnel. The inmates fought the attacking guards and started a fire, as members of rival gangs took advantage of the confusion to settle scores. Then, as news of the conflagration broke, relatives of inmates gathered outside the prison, demanding information. When this was not forthcoming, they began to throw stones at the guards, fought back police, took over a roadway, and set several buses on fire.