Shinzo Abe, former Japan prime minister, shot during speech

Shots were heard and a white puff of smoke was seen as Abe made a campaign stump speech outside a train station.

An NHK reporter on the scene said they could hear two consecutive bangs during Abe's speech.

"He was giving a speech and a man came from behind," a young woman at the scene told NHK. "The first shot sounded like a toy. He didn't fall and there was a large bang. The second shot was more visible, you could see the spark and smoke," she added. "After the second shot, people surrounded him and gave him cardiac massage."

National broadcaster NHK said a man in his 40s had been arrested for attempted murder and a gun had been confiscated from him, citing police sources.

Police identified the suspected shooter as Tetsuya Yamagami, a resident of Nara. He's a former member of the Japanese Maritime Self-Defense Force. Police say the gunman admitted he tried to kill Abe because he was 'dissatisfied' with him.

Abe, 67, appeared to be in a state of cardiac arrest, the network said and Kyodo news agency. 

He remains in hospital without vital signs after being shot.

Abe served two terms as prime minister to become Japan's longest-serving premier before stepping down in 2020 citing ill health.

But he has remained a dominant presence over the ruling Liberal Democratic party (LDP) party, controlling one of its major factions.

His protege, Prime Minister Fumio Kishida, faces an upper house election on Sunday in which analysts say he hopes to emerge from Abe's shadow and define his premiership.

Abe has been best known for his signature “Abenomics” policy featured bold monetary easing and fiscal spending.

He also bolstered defence spending after years of declines and expanded the military’s ability to project power abroad.

In a historic shift in 2014, his government reinterpreted the postwar, pacifist constitution to allow troops to fight overseas for the first time since World War Two.

U.S. Secretary of State Antony Blinken expressed deep concern over Abe's condition.

"Our thoughts, our prayers are with him, with his family, with the people of Japan," Blinken said on the sidelines of a G20 meeting on the Indonesian island of Bali. "This is a very, very sad moment. And we're awaiting news from Japan."

The United States is Japan's most important ally.

Japan has some of the world's toughest gun-control laws, and annual deaths from firearms in the country of 125 million people are regularly in single figures.