What in the world happen??

Got home last night, with only one of our ten chickens in the coop. Found one dead(breast half eaten) , and three hiding. The rest came back this morning. ALL of them are missing feathers. Two are hurt worse. There were feathers all the way around our house... Any ideas on what would or could do this at one time? All of this took place within a couple of hours. Thanks

 

We live in the county. In the middle of nowhere! They are free range during the day, and we lock the coop up at night. No fence just a coop. We have lost 7 in the last year and a half. But nothing ever like this. From all the feathers we thought they were all dead. There is a dog who has gotten two. But it has never looked like this. What we don't understand is how something could get a hold of all of them in one time. It does not look like they were gotten out of the coop. But around it was feathers and then feathers all the way on the other side of our house. It was just strange to us. We know things will eat them or get after them, but this time it was how it was done that we just can't figure out!