A 24-year-old man dressed in Batman's Joker costume attacked passengers on a Tokyo train line on Sunday evening, injuring about 10 people as many party-goers headed into the city centre for Halloween gatherings, media reported.

Police arrested the suspected attacker on the spot, media reported.

A man in his 60s was unconscious and in critical condition after being stabbed, while witnesses also said the attacker had spread fluid around...