What will get into your coupe... (under the fence) Kill 3 chickens, Most likely fatally wound another, but leave 5 othes perfectly healthy, and the ones that were dead, didn't look mangled, one of the other chickens was pecking one, so it looked a little rough. Whatever it was, it's gone and didn't even try to eat it's harvest... Critters are poachers.
I would suspect a raccoon first. They are the only chicken predator that I think just likes to kill. I have been hit by weasels and fox. Chickens were dead and headless or missing. Put a game cam out. It (whatever it is) will likely be back.
The chicken wire was stretch rather high... I'd say enough for your average dog to get under... I was thinking maybe a stray neighborhood dog happened by, had some fun, and went on his way... all I know is when I got home I had live chickens out and dead ones in.
I'm not a chicken guy but that was my first thought as well. Had chickens growing up and some dogs killed them for sport. That's the day I found out my mom could run just as fast as a dog. She'd give them hell for killing our chickens.
All 6 of my chickens were killed by my neighbors dog recently. Just killed them and left them lay except for the one he took back to his yard to chew on.