On 21 May 2014, a Taiwanese man carried out a stabbing spree targeting random civilians on a Taipei Metro C321 train near Jiangzicui Station, resulting in four deaths and 24 injuries.

[4] Before the train could stop at Jiangzicui Station, a group of passengers banded together to distance themselves using umbrellas while others tried to discourage the attacker by loudly taunting him.

[5] According to statistics compiled by the New Taipei Fire Department, the youngest victim was a 26-year-old graduate student at National Cheng Kung University, identified as Chang Cheng-han (male).

[4][6] Cheng Chieh (Chinese: 鄭捷), also romanized as Zheng Jie, was born 3 April 1993 in the Banqiao District, and attended schools in Taipei.

[11][12] School officials there had noticed Cheng's startling social media activity and offered him counseling before the incident, but no irregularities were discovered.

[19][20] Trainset number 117/118, which was the setting of the stabbing attack, was temporarily withdrawn from service after arrival at Jiangzicui Station and underwent disinfection and change of seats.

[21] New Taipei Police Chief Chen Kuo-en [zh] identified the suspected attacker as Cheng Chieh, a 21-year-old second-year student at Tunghai University in the central city of Taichung.

[2][22] During questioning, the suspect said he originally intended to attack after his college graduation, but decided to move earlier since he had "no classes" on 21 May and he had grown tired of living.

[23][24] The suspect stated that he did not admit guilt, felt no regret, wanted the death sentence, and that even if his parents were on the train he attacked, he would have killed them, as well as the prosecutors questioning him.

[25] On the evening of 21 May, people began leaving flowers and cards at an exit of Jiangzicui Station to pay tribute to those who died in the attack.

[26] On 22 May, President Ma Ying-jeou condemned the attack and ordered the National Police Agency to investigate what led a university student to stab four people to death on a crowded subway train.

[28] General manager Tan Gwa-guang of the Taipei Rapid Transit Corporation stated that the company would pay the medical expenses of the victims and set aside NT$4 million to compensate their families.

[34] Lin Hsin-yi [zh], executive director of the Taiwan Alliance to End the Death Penalty, said that the most important thing at present is for the public to think about how to help the victims of the metro slashing spree and ease the survivors and their relatives out of the suffering brought about by the tragedy.

[46][47][48] On 7 August, the New Taipei District Court ordered Cheng to pay approximately NT$30 million to ten victims of the attack.