A woman places a flower for the victims outside the Vladislav Ribnikar elementary school in the capital Belgrade, on May 4, 2023, a day after a 13-year-old suspect shot dead eight fellow students and a security guard after allegedly drawing up a kill list. - The tragedy has left the Balkan nation reeling. Gun violence at schools is extremely rare in Serbia and the country's president called Wednesday's shooting "one of the most difficult days" in recent history. (Photo by OLIVER BUNIC / AFP)