In Nazi usage, "euthanasia" referred to the killing of those whom the Nazis deemed "unworthy of life." In 1941 the Hadamar psychiatric clinic served as one of the euthanasia killing centers in Germany. Patients selected by German doctors for euthanasia were transferred to Hadamar or one of the other facilities and were killed in gas chambers. Over 10,000 people were gassed at Hadamar before the Euthanasia Program officially ended in August 1941. Although the program had officially ended, killings continued at Hadamar by means of lethal injections. After the war, US personnel filmed the facility and cared for surviving patients.