Investigators confiscated two cylindrical objects from the scene believed to be explosive devices, NHK reported. One exploded during the incident, while a police officer seized the other as the suspect, Ryuji Kimura, a 24-year-old from Kawanishi, Hyogo Prefecture, was being held down, the broadcaster said. The suspect has so far not responded to police questioning but has said he will talk once his lawyer arrives. No injuries were reported following the incident.