Nazis killed the disabled first

from https://en.wikipedia.org/wiki/Victims_of_Nazi_Germany

Those with disabilities were among the first to be murdered by the
Nazis; according to the U.S. Holocaust Memorial Museum, the T-4
Program (established in 1939) was the model for future Nazi
exterminations and it set a precedent for the genocide of what they
described as the Jewish race.[62] The program attempted to maintain
the "purity" of the Aryan race by systematically murdering children
and adults with physical deformities or suffering from mental illness,
using gas chambers for the first time. Although Hitler formally halted
the program in late August 1941, the killings secretly continued until
the end of the war and an estimated 275,000 people with congenital
disabilities were murdered.[63]