Overcrowding in the ghetto was exacerbated by the influx of some 40,000 Polish Jews forced out from the surrounding Warthegau areas, as well as by the Holocaust transports of foreign Jews resettled to Łódź from Vienna, Berlin, Cologne, Hamburg and other cities in Nazi Germany, as well as from Luxembourg, and the Protectorate of Bohemia and Moravia including the citywide Theresienstadt concentration camp.[5] Heinrich Himmler visited the ghetto for the first time on 7 June 1941.[23] On 29 July 1941, following an inspection, most patients of the ghetto's psychiatric hospital were taken away never to return. "They understood, for example, why they had been injected with tranquilizers in the night. Injections of scopolamine were used, at the request of the Nazi authorities." Situated 50 kilometres (31 mi) north of Łódź in the town of Chełmno, the Kulmhof extermination camp began gassing operations on 8 December 1941.