Genocide has occurred through many different mechanisms. You are dithering about the exact form in order to engage in genocide denial. You should be ashamed.

The Nazis’ genocide was not only their death camps, either, which you would know if you cared about the history or this topic. They would massacre entire villages, turn neighborhoods into ghettos and kill entire masse, including when they fought back (like the Warsaw Ghetto), they would shoot individuals on the spot when they were located. They would siege civilian centers and starve or kill at will.