People laid out flowers and cards to pay tribute to those who died in the attack at Jiangzicui station on Wednesday evening.
Three people – a 28-year-old man, 26-year-old man and 47-year-old woman – died at the site from stab wounds to the neck and chest, while a fourth victim, a woman, 62, died in hospital.
The lone attacker, Cheng Chieh, a 21-year-old college student, is in custody undergoing further questioning.