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. Consequently, the city was heavily bombed by the Luftwaffe on 6 April 1941, when up to 24,000 people were killed. Yugoslavia was then invaded by German, Italian, Hungarian, and Bulgarian forces, Belgrade was occupied by the German Army on 13 April 1941 and suburbs as far east as Zemun, in the Belgrade metropolitan area, were incorporated into a Nazi state, the Independent State of Croatia. Belgrade became the seat of the Nedić regime, headed by General Milan Nedić.