My Grandmother lived in Leipzig her whole life. When WW2 broke out she was 12 year old, and she found the war to be a welcome change compared to the monotony of every day life. These attitudes would change in time of course due to the things she saw. Regardless, the US army occupied Leipzig for a couple months before the German surrender. During the period of US control, my Grandmother reported US helicopters flying low over the streets of Leipzig and firing indiscriminately, shooting at anything which moved. At this point she claims to have decided she hated the Americans, and was optimistic about the new Soviet occupation, an optimism which would stay with her and then her husband, until the 1970s. Regardless, after light research, I could not find any other accounts of US military misconduct in Leipzig. Is there any other information like this, or at least any other first person accounts which correlate with her story?
As told, it is quite impossible to be true, as the US didn't have helicopters in any meaningful sense in 1945. It sounds like she is confusing scenes from Full Metal Jacket with real life, to be perfectly frank, since even sans helicopters, American troops weren't slaughtering civilians with reckless abandon in Leipzig, or any other German city for that matter.
That said, American conduct in Germany was hardly perfect. I've written extensively about looting by American troops during World War II in this older post which might be of interest.