Japanese Prime Minister Fumio Kishida was evacuated unhurt after someone threw an explosive device in his direction while he was campaigning at a fishing port in western Japan, officials said.
Police wrestled a suspect to the ground as smoke filled the air and screaming bystanders scrambled to get away.
Although no one was hurt and Mr Kishida continued campaigning on Saturday, the chaotic scene was reminiscent of the assassination nine months ago of former prime minister Shinzo Abe, which also came on a campaign tour and continues to reverberate in Japanese politics.
A young man believed to be a suspect was arrested at the scene allegedly throwing “the suspicious object”, chief cabinet secretary Hirokazu Matsuno told reporters.
Mr Matsuno refused to comment on the suspect’s motive and background, saying police are still investigating.
His security detail suddenly points to the ground near him and the Prime Minister whips around, looking alarmed.
The camera quickly turns to the crowd just as several people, including uniformed and plainclothes police officers, converge on a young man wearing a white surgical mask and holding what appears to be another device in a long silver tube.
The crowd scatters in panic as police roughly drag the man away.
It was not immediately clear what the explosive device was or how many the suspect had, but some reports said it was a smoke or pipe bomb, possibly with a delayed fuse.
No injuries were reported in the incident, which came on the eve of a major international forum in Japan.
Mr Kishida continued his campaign speeches later on Saturday, Mr Matsuno said.
Mr Kishida did not mention the explosion and returned to the Tokyo region in the evening after campaigning in Chiba for another candidate.
“Elections are the core of democracy and we should never tolerate threats or obstruction by violence,” Mr Matsuno said.
He said he instructed national police to make sure of their utmost effort for the protection of dignitaries who are visiting Japan in the period leading up to the Group of Seven summit in May.
Amid a national outcry, police have tightened their protective measures following a subsequent investigation that found holes in Mr Abe’s security.
Security has been also ramped up in Japan as senior diplomats from some of the world’s most powerful democracies arrive for Sunday’s G-7 foreign minister meetings.
Mr Kishida will host a May 19-21 G-7 leaders’ summit in his hometown of Hiroshima.
One witness on Saturday told NHK television she was standing in the crowd when she saw something come flying from behind.
After a sudden loud noise, she fled with her children.
Another witness said people were screaming and he saw someone being apprehended right before the explosion occurred.
Saturday’s attack comes ahead of nationwide local elections, including several by-elections for vacated parliamentary seats, with voting scheduled for April 23.
The suspect, Tetsuya Yamagami, has been charged with murder and several other crimes, including violating the gun control law.
He told investigators he killed Mr Abe, one of Japan’s most influential and divisive politicians, because of the former prime minister’s apparent links to a religious group that he hated.
In statements and social media postings attributed to him, Yamagami said he developed a grudge because his mother had made massive donations to the Unification Church that bankrupted his family and ruined his life.
Mr Abe’s assassination led to the resignation of top local and national police chiefs and a tightening of security guidelines for political leaders and other prominent people.
Mr Kishida’s government was hoping to focus world attention this weekend on the hot spring resort town of Karuizawa, where senior diplomats will gather Sunday for the so-called Group of Seven foreign ministers’ meeting.
The foreign ministers from Japan, the United States, the United Kingdom, France, Germany, Canada, Italy and the European Union are expected to focus on worries over Russia’s war in Ukraine, China’s increasingly belligerent rise and North Korea’s provocative string of weapons tests.