Sorry for your loss. Unfortunately I had the same thing happen last night; although every one of my chickens was killed. It has been suggested it was also a weasel as it killed them all but didn't eat them.
I have to warn you though; I had thick boards sunk into the ground about 6" all the way around the base of my coop and whatever it was still managed to dig under to get in. I'm thinking 6" is not enough. If I decide to re-use my coop, I will only do so once I have hardware cloth securely fastened to the entire bottom of the coop preventing anything from digging thier way in.
I have to warn you though; I had thick boards sunk into the ground about 6" all the way around the base of my coop and whatever it was still managed to dig under to get in. I'm thinking 6" is not enough. If I decide to re-use my coop, I will only do so once I have hardware cloth securely fastened to the entire bottom of the coop preventing anything from digging thier way in.