The assassination of Japan's longest-serving leader has stunned a nation where gun violence is extremely rare.

Police on Friday investigated the home of the man suspected of using an improvised firearm to assassinate former Japanese Prime Minister Shinzo Abe and said they seized multiple weapons that also appeared to be homemade.

The discovery followed the arrest of the suspect  identified by officials as Tetsuya Yamagami, in the western Japanese city of Nara, where Abe was delivering a campaign speech outdoors ahead of parliamentary elections this weekend.

Local media captured video and photos of the bulky weapon that police said was used to kill Abe. They confirmed that the firearm consists of two metal barrels attached to a wooden board and is more than a foot long.

"We are conducting forensics, but clearly it looks homemade," a Nara police chief said at a news conference.

Police said several weapons were also found at Yamagami's residence and were similar to the firearm believed to be used to shoot Abe. They added that it was unclear whether the suspect had the proper licenses for the weapons.

The shooting death of Abe, Japan's longest-serving leader before resigning in 2020 because of health issues, has stunned a nation where gun violence is extremely rare.

Japan, a nation of about 125.8 million people, has one of the strictest gun laws in the world. There were just 10 shootings in 2021, with one person killed and four people injured, according to the country's National Police Agency. The majority of shootings each year are linked to Japanese organized crime, the agency added.

Witnesses at Friday's scene described a "loud bang and then smoke" set off by the first shot, BBC reported. In dramatic videos, Abe could be seen raising his fist just before the shots rang out. He collapsed to the ground with blood staining his white shirt and bystanders rushing to his aid.