US President Joe Biden on Friday said former Japanese prime minister Shinzo Abe's vision of a "free and open Indo-Pacific will endure as he expressed outrage over his assassination and underlined that gun violence always leaves a deep scar on the communities that are affected by it.

"I am stunned, outraged, and deeply saddened by the news that my friend Shinzo Abe, former Prime Minister of Japan, was shot and killed while campaigning. This is a tragedy for Japan and for all who knew him, "Biden said in a statement.

Noting that he had the privilege to work closely with Abe, Biden said as the longest serving Japanese Prime Minister, Abe was a champion of the "alliance between our nations and the friendship between our people and his vision of a "free and open Indo-Pacific will endure.

Abe, 67, was shot from behind in Nara in western Japan while giving a campaign speech. Public broadcaster NHK said police have arrested a Nara resident in his 40s, who allegedly used a handmade gun to shoot Abe, a tragedy that has shocked Japan which has some of the strictest gun laws in the world.

Biden, who is dealing with mass shootings in the US, said gun violence always leaves a deep scar on the communities that are affected by it.

Biden said while there are many details that are not yet known about the attack, we know that violent attacks are never acceptable and that gun violence always leaves a deep scar on the communities that are affected by it.

The US President said Abe cared deeply about the Japanese people and dedicated his life to their service.

Even at the moment he was attacked, he was engaged in the work of democracy, he said, adding that the United States stands with Japan in this moment of grief and he sent his deepest condolences to Abe's family.