Japan's former Prime Minister Shinzo Abe has died after being shot during a campaign speech in western Japan, public broadcaster NHK said Friday.

Abe, 67, had been delivering a stump speech near a train station in the western city of Nara when he was shot by an assailant.

Prime Minister Fumio Kishida condemned the shooting in the western city in the "strongest terms," while Japanese people and world leaders expressed shock at the assassination attempt in a country in which political violence is rare and guns are tightly controlled.

Struggling to keep his emotions in check, Kishida said Abe, 67, was in grave condition.

"Everything that can be done is being done to revive him. I'm praying from the depths of my heart that his life will be saved," Kishida told reporters, adding he was not aware of any motive.

"This attack is an act of brutality that happened during the elections – the very foundation of our democracy – and is absolutely unforgivable."

Police said a 41-year-old man suspected of carrying out the shooting had been arrested. NHK quoted the suspect, identified as Tetsuya Yamagami, as telling police he was dissatisfied with Abe and wanted to kill him.

Chief cabinet secretary Hirokazu Matsuno earlier told reporters that Abe was shot at around 11:30 a.m. "One man, believed to be the shooter, has been taken into custody. The condition of former prime minister Abe is currently unknown."

"Whatever the reason, such a barbaric act can never be tolerated, and we strongly condemn it," Matsuno added.

The former leader had been delivering a stump speech at an event ahead of Sunday's upper house elections when the apparent sound of gunshots was heard, national broadcaster NHK and the Kyodo news agency said.

NHK and Kyodo both reported Abe was taken to hospital and appeared to be in cardiorespiratory arrest – a term used in Japan indicating no vital signs, and generally preceding a formal certification of death by a coroner.

It was a stunning development in a country with famously low levels of violent crime and tough gun laws, involving perhaps Japan's best-known politician.

"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 collapsed and was bleeding from the neck, a source from his ruling Liberal Democratic Party told the Jiji news agency.

Neither the LDP nor local police were able to immediately confirm the reports.

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

Several media outlets reported that he appeared to have been shot from behind, possibly with a shotgun.

An official at Nara Medical University hospital told Agence France-Presse (AFP): "What we can share now is that his transfer here has been completed," declining to comment on the former leader's status.

Jiji said the government said a task force had been formed in the wake of the incident, and reactions were already beginning to pour in.

The United States ambassador to Japan, Rahm Emanuel, said he was "saddened and shocked" by the shooting.

"We are all saddened and shocked by the shooting of former prime minister Abe Shinzo. Abe-san has been an outstanding leader of Japan and unwavering ally of the United States. The U.S. Government and American people are praying for the well-being of Abe-san, his family, and people of Japan," Emanuel said in a statement.

Prime Minister Fumio Kishida's special advisor Gen Nakatani told reporters "terror or violence can never be tolerated," Jiji reported.

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 license 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.