I guess I'm lucky we haven't had a problem here in the daytime, but at night the Raccoons will get to them. I too lost an entire flock one year over the course of just a few nights. And they were locked "safely" inside their house. Raccoons are crafty and will get in, any way possible. Obviously I read your post and I know your not dealing with Raccoons, I just wanted you to know that I've been there too, and almost everyone that has ever raised chickens have lost some to predators. As a friend of mine put it, after dark they turn into pumpkins and predators know they are easy prey. We just have to make it so they are not easy to access for predators.
I know this is a tough time for you, but don't let this misfortune end you BYC farm. If it were me I'd be working on making that outside fence in penetrable, or as close to it as you can get. Please use this as a learning experience and try again, I'm sure it will be much more rewarding, and you will be much wiser.
Rob