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"There was a gaping hole in the heart attributed to the gun wound," a doctor said. He was shot twice in the neck, doctors have said.
Former prime minister Shinzo Abe was shot in Nara, Prime Minister Fumio Kishida told reporters earlier in the day as he abandoned his campaign trail and flew to Tokyo. "It is absolutely unforgivable. I condemn this act in the strongest terms," he said.
One man, believed to be the shooter, has been taken into custody, chief cabinet secretary Hirokazu Matsuno said. Local media identified the man as 41-year-old Tetsuya Yamagami, citing police sources. Explosives have been found at his house, say officials.
Shinzo Abe was delivering a speech at an event ahead of Sunday's upper house elections when gunshots were heard, NHK and the Kyodo news agency said.
"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."
Abe, 67, collapsed and was bleeding from the neck, a source from the ruling party told the Jiji news agency. An official of Abe's faction of the party said he underwent transfusions, reports said.
Several media outlets reported that he appeared to have been shot from behind, possibly with a shotgun.
The government said a task force had been formed in the wake of the incident and the top government spokesman was expected to speak shortly.
Abe, Japan's longest-serving prime minister, held office in 2006 for one year and again from 2012 to 2020, when he was forced to step down due to the debilitating bowel condition ulcerative colitis.
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. Getting a gun licence is a long and complicated process even for Japanese citizens, who must first get a recommendation from a shooting association and then undergo strict police checks.
With inputs from AFP
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