I have 14 ducks in an enclosure that is up against my house. It has three sides to it and my house is the forth side. I found online a device called Nite-Guard. It's a solar powered Flash of Danger that repels predators. I bought three of them and put them on all three exposed sides of their large pen. It flashes a red light at night and is supposed to keep predators away at night. My two neighbors that live not far have both lost flock birds to predators. I have never lost one and have had mine for 3 years now. They are not put in an enclosure at night and have free range of the pen all night long. This seems to work for me. A raccoon got my Son's flock years ago where he lives and it did exactly what you described happened to yours. I am so sorry for your loss. Good luck in saving the rest of your flock.