The marriage produced three children : On 29 August 1935 , while the King and Queen were driving along the winding , narrow roads near their villa at Küssnacht am Rigi , Schwyz , Switzerland on the shores of Lake Lucerne , Leopold lost control of the car which plunged into the lake , killing Queen Astrid .
On 29 August 1935 , the King and Queen were driving along the winding , narrow roads near their villa at Küssnacht am Rigi , Schwyz , Switzerland on the shores of Lake Lucerne .