On 25 March 1941, the government of regent Crown Prince Paul signed the Tripartite Pact, joining the Axis powers in an effort to stay out of the Second World War and keep Yugoslavia neutral during the conflict. This was immediately followed by mass protests in Belgrade and a military coup d'état led by Air Force commander General Dušan Simović, who proclaimed King Peter II to be of age to rule the realm. As a result, the city was heavily bombed by the Luftwaffe on 6 April 1941, killing up to 2,274 people. Yugoslavia was then invaded by German, Italian, Hungarian, and Bulgarian forces. Belgrade was captured by subterfuge, with six German soldiers led by their officer Fritz Klingenberg feigning threatening size, forcing the city to capitulate. Belgrade was more directly occupied by the German Army in the same month and became the seat of the puppet Nedić regime, headed by its namesake general. Some of today's parts of Belgrade were incorporated in the Independent State of Croatia in occupied Yugoslavia, another puppet state, where Ustashe regime carried out the Genocide of Serbs.