Awww, your poor kids. I am so sorry this happened. Maybe you can get replacements...to help the kids.
Edited to say.....If you need another roo...and are not particular...I have a GREAT Cuckoo Maran Roo. He is now 18 weeks. It would be a bit of a drive, but if you are up for it....let me know. We thought we had a breeding pair...we have 2 roos. UGH!
A lot depends on the dog...some will kill and eat what they kill, others will just kill. Cats are the same way. I've seen 'em kill young rabbits, birds, rats, mice and just leave the things, other times they'll eat about half of whatever it is they killed.
I bet it was a dog too. We just lost one of our favorite Chicks to our Lab. She snuck in and grabbed her so fast , killed her and dropped her. My kids haven't been able to even look at our dog since. So sad.
A dog got 4 of hens too. I guess she thought they were play toys or just wanted to kill them. Did not try to eat any of them. But feathers everywhere. I'll never forget what I came home to that day. I still have anixety everytime I come home now. I know how I felt so I can only imagine how horrifying it was to your kids. More chickens helped my daughter get over the loss, and me. But if it was a dog. If it gets loose again, it will probably be back. Be extra cautious.
Good Luck.
From the sound of it I would almost bet it was a dog, and not a true stray either, somebodys pet.
If it had been a ferrel dog it would have carried them off and eaten them.
If it were a cat you'd most likely find a small puncture
along the spine.