About 120 people were killed on two subway trains in Daegu, South Korea, today after a man lit a carton filled with an unidentified material that burst into flames. Motivation for the attack is still unknown, but the suspect allegedly has a history of mental illness. The fire began in a six-car train at a station, igniting seats and spreading to another train also stopped at the station, reported the Associated Press. People were killed by asphyxiation from the fumes or by being burnt by the fire itself. Another 138 people were injured, many of them seriously. The fire was put out about three hours after it began, but toxic gas in the tunnel delayed rescue efforts.