If a prop came off a piston engine under power, it would have made a distinctive sound, sort of like a zipper being pulled.
I’ll have to ask my neighbor to describe it again.. she said that she heard a plane making some kind of odd sound that caught her attention, and then she actually heard the crash. That’s when she headed outside to go look for it.
I was maybe 50 feet away from her house and didn’t hear a thing until all of the sirens started up. But when you looked north you could see the big black smoke plume.