The operator of Taiwan's subway system said yesterday that it was seeking compensation for operational losses from a man who killed four people in a stabbing spree last month. The Taipei Rapid Transit Corporation said it lost about 945,000 passengers in the 10 days following the May 21 attack, or the equivalent of NT$20.6 million (HK$5.30 million) in revenue. The transit corporation filed suit on Wednesday seeking damages in that amount from accused subway attacker Cheng Chieh. Cheng, a 21-year-old college student, killed four people and wounded nearly two dozen others in the first fatal attack on the city's subway system since it opened in 1996. He said he had said he wanted to do a big thing like this since his childhood Taipei police The incident shocked Taiwan and has triggered panic among edgy commuters. Several passengers fled a train when they mistook an autistic man for an attacker last week. On Wednesday, three people were slightly injured when passengers panicked when a man had an epileptic seizure. Security has been strengthened in the metro, which carries about 1.85 million commuters a day. According to the police, Cheng had said he wanted to do "a big thing such as this since his childhood" and originally planned to carry it out after graduating college. Local media said he had been obsessed with online killing games and had written horror stories. Cheng's parents apologised to the victims' families and asked for their son to be executed as soon as possible.