Kosta Kecmanović, a 13-year-old Serbian student, killed eight of his classmates and a security guard in a school shooting at Vladislav Ribnikar Elementary School in Belgrade on May 3, 2023. The attack was carefully planned for a month, during which Kosta drew sketches of classrooms and compiled a "kill list" of people he intended to target. He used his father's licensed firearms, which were kept in a safe, but he apparently knew the code to access them. The motives for his attack remain unclear, but the shooting was seen as an extreme outburst potentially linked to the availability of weapons and underlying social issues. Kosta himself expressed regret later but did not provide a specific reason for his actions during questioning. His parents were later convicted for failing to secure the firearms properly and child neglect.