NHK has learned that police have seized what appears to be gunpowder from the home of a man suspected of hurling an explosive device toward Japanese Prime Minister Kishida Fumio.

The 24-year-old suspect, Kimura Ryuji, allegedly committed the act on Saturday when the prime minister was about to give a speech at a fishing port in the western city of Wakayama.

The prime minister was evacuated unharmed. One police officer was slightly wounded. Kishida was there to lend support to a Lower House by-election candidate.

Kimura was arrested on the spot.

Investigators began to search his home in the city of Kawanishi, Hyogo Prefecture, early on Sunday morning and ended the operation shortly after 9 a.m.

The investigators removed more than 10 cardboard boxes believed to contain relevant materials from the suspect's home.

They have so far seized his personal computer, his mobile phone and what appears to be gunpowder.

A family member who lives with the suspect told police that he was at home on the night before the incident but was gone on the following morning.

Kimura has given investigators no specific statements on the incident. Police are planning to analyze data on his electronic devices and interview relevant people to determine why and how he caused the incident.