Flames broke out in an overcrowded Turkish prison after inmates lit a mattress on fire, Turkish authorities said Sunday. Thirteen prisoners died in the blaze. Turkish Prime Minister Recep Tayyip Erdogan say that a fight that began inside a prison ward Saturday led prisoners to start the fire. It is a tactic that’s been used before in Turkish prison riots, and rescue efforts were hampered by barricades the prisoners erected at the ward’s entrance. Five survivors were taken to the hospital for treatment. The prime minister said he will launch an investigation into whether there is overcrowding at the prison.