How do the Balicki children escape from their home when the Nazis come?

Joseph Balicki, a Polish schoolteacher, is taken to a prison camp by the Nazis for turning a picture of Hitler to the wall in class. While Joseph is incarcerated, the Germans come to his house to take his wife away. When Joseph escapes from the camp and returns to the smoldering ruins of his home, one of his neighbors tells him that his wife was seized by the Gestapo and probably sent to Germany as a slave laborer.
On the night that the Gestapo come to take Mrs. Balicki away, Joseph's son Edek fires shots at the Germans' van, a brave but dangerous thing to do. His sister Ruth admonishes him for his rashness and impetuosity. Exchanging fire with the Germans is utterly futile; the Balicki children need to escape, and fast. So they climb up onto the roof and make their way across the rooftops of adjacent houses. From a distance, the children watch as the Nazis blow up their house.