Taipei, Rajab 22, 1435, May 21, 2014, SPA -- A university student wielding a knife attacked riders aboard a subway train in Taiwan's capital on Wednesday, killing four people and injuring at least 21 others, police and local media said. The seemingly random attack occurred at about 4 p.m. at the start of the evening rush hour aboard a train on Taipei's Banqiao line, which leads to the city's southwestern suburbs, AP reported Speaking to reporters, Chen Kuo-en, the police chief of Xinbeishi, where Jiangzicui station is located, identified the attacker as a 21-year-old second-year student at Tunghai University in the central city of Taichung. Chen said the man told police he had wanted to do something "shocking and big" and had plotted to carry out the attack from childhood. Chen said no other motive was presently known and the suspect had no record of mental health problems. "He's aware of the legal responsibility of his crime," Chen said. Police said a 47-year-old woman and two men, one in his 20s and the other in his 30s, were declared dead on arrival at hospital. A 62-year-old woman died in surgery four hours after the attack. --SPA 19:55 LOCAL TIME 16:55 GMT www.spa.gov.sa/w