The people of Görlitz had to spend the night in sports halls and schools, after flood warnings were called on Saturday. The towns of Rothenburg, Bad Muskau and Zodel are also badly affected.
The state's premier Stanislaw Tillich, Interior Minister Markus Ulbig and Environment Minister Frank Kupfer are all expected to travel to the affected area on Sunday. The floods have also forced the cancellation of a meeting between the German and Polish interior ministers Thomas de Maiziere and Jerzy Müller.
One man was fished out of high waters south of Görlitz with the help of a rescue helicopter. He was admitted to hospital with hypothermia and other injuries.
The northern and southern parts of the town are currently inaccessible, according to local authorities, and as yet there are no estimates of the extent of the damage. The water is reported to have poured into the town in the space of a few hours.