The Serbian prime minister was forced to flee a ceremony commemorating the 20th anniversary of the Srebrenica massacre on Saturday, after he was pelted with stones and plastic bottles. The Bosnian presidency condemned Saturday’s attack on Serbian Prime Minister Aleksandar Vucic, saying he had attended the ceremony in a “spirit of reconciliation.” The event marked 20 years since the massacre of 8,000 Muslim men and boys by Bosnian Serbs led by General Ratko Mladic during the Bosnian War. It’s recognized as Europe’s single worst atrocity since the end of World War II.