World leaders expressed shock and sadness after former Japanese Prime Minister Shinzo Abe was shot and killed Friday in western Japan while giving a campaign speech.

U.S. President Joe Biden offered condolences to Abe's family. "This is a tragedy for Japan and for all who knew him," he said in a statement.

Biden spoke about his personal connection with Abe.

"I had the privilege to work closely with Prime Minister Abe. As vice president, I visited him in Tokyo and welcomed him to Washington. He was a champion of the alliance between our nations and the friendship between our people," Biden said. "The longest-serving Japanese prime minister, his vision of a free and open Indo-Pacific will endure.

"Above all, he 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."

Biden said he had ordered the U.S flag to be flown at half-staff to honor Abe.

U.S. Secretary of State Antony Blinken released a statement saying, "Prime Minister Abe was a global leader and unwavering ally and friend of the United States, whose vision of a free and open Indo-Pacific lifted our alliance cooperation to new heights."

Former U.S. President Barack Obama said in a statement, "Abe was devoted to both the country he served and the extraordinary alliance between the United States and Japan. I will always remember the work we did to strengthen our alliance, the moving experience of traveling to Hiroshima and Pearl Harbor together, and the grace he and his wife, Akie Abe, showed to me and Michelle."

Current Japanese Prime Minister Fumio Kishida condemned the "unforgivable act," saying, "The free and fair election, which is the root of democracy, needs to be protected no matter what. We will not be defeated by violence."

A spokesman for U.N. Secretary-General Antonio Guterres also issued a statement Friday.

"The secretary-general recalls Shinzo Abe's commitment to promoting peace and security, championing the Sustainable Development Goals and advocating for universal health coverage,' said Farhan Haq. "As the longest-serving prime minister, he was dedicated to reviving his country's economy and serving the people of Japan."

In Britain, Queen Elizabeth also tweeted her condolences.

"My family and I were deeply saddened to hear the news of the sudden and tragic death of former prime minister, Shinzo Abe," the queen said. "I have fond memories of meeting Mr. Abe and his wife during their visit to the United Kingdom in 2016. His love for Japan, and his desire to forge ever-closer bonds with the United Kingdom were clear."

Indian Prime Minister Narendra Modi said he was "shocked and saddened beyond words." Modi also said that India would observe one day of national mourning on Saturday to respect the former prime minister.

Many other world leaders reacted to the news, including leaders of Canada, Germany, Pakistan, Sweden, the Philippines, Australia, Spain, France and Italy.

The International Olympic Committee praised Abe's "vision, determination and dependability," which enabled the postponement of the Tokyo Olympics for one year because of the global spread of the coronavirus. The IOC said it would have the Olympic flag flown at half-staff in the Olympic house in Lausanne, Switzerland, for three days.