At Least fifteen people were injured after a man had spread a hydrochloric acid around the train and set it on fire on the Keio Line train in Tokyo, according to Kyodo News.
Police immediately arrested the suspect, who was carrying a knife.
A video circulating on Twitter showed passengers evacuating through windows to escape the train.
The suspect is being questioned by the police. The man is believed to be around age 20 years old, according to reports. Six ambulances arrived at the site of the incident.
The incident took place at around 8:00 p.m. local time on Sunday.