Nine inmates have been killed and their bodies set on fire in a riot at a prison in Brazil's Goias state, officials said.Military Police Commander Divino Alves told the media the melee broke out on Monday between members of rival gangs at the prison in Aparecida de Goiania, the second largest city in the state, and it took officials nearly two hours to restore order, Xinhua reported.The Executive Superintendence of Prison Management said in a statement that inmates in section C of the prison invaded section B, and started a fire.Firefighters were called in to battle the flames, and smoke could be seen rising from the facility.Another 14 inmates were injured in the fighting and they returned to their cells after receiving emergency treatment, according to Brazil's G1 news website.As many as 106 prisoners took advantage of the mayhem to escape, and officials have captured 29, the report said, adding that "another 127 left the prison due to the confusion, but returned voluntarily after the situation died down."Officials were searching for the other escapees.Prison riots are fairly common in Brazil, where the overpopulation of prisons is a pervasive problem.