Japan marked the 69th anniversary of the Hiroshima bombing on Wednesday with prayers and paper lanterns, as the city's mayor called on world leaders to stop the proliferation of nuclear weapons. About 45,000 thousand people observed a minute of silence at the city's Peace Park, near the epicenter of the 1945 bombing that killed up to 140,000 people. Another bombing at Nagasaki three days later killed another 70,000, prompting Japan to surrender in World War II. U.S. Ambassador Caroline Kennedy, survivors, their descendents and other dignitaries were on hand to listen to Mayor Kazumi Matsui urge world leaders to visit the bomb-scarred cities.