Stupid thing posted beofre I was done. Is it possible they may be underneath your coop or have found somewhere to hide on your property? If not then I would start looking around the edges of your property for chicken poop. Is it possible that there might be a sound they would relate to home, like shaking of Feed in a canister? I know my girls come running when they hear me shake the food scoop. I would also ask your neighbors if they had heard or seen anything unusual, like heard a lot of chirping. I would expect that if they went running from the coop they would have continued running in the same direction their Coop door opens, unless the dog kept chasing them, they would have stopped eventually. When I lost a girl I found a big pile of feathers, then a trail of individual feathers that went into the woods. I didn't even see the individual feathers at first, but once I saw the first one there was a trail through the woods to a smaller pile of feathers and the trail stopped there. I assume whatever got her had caught up to her then. In your case, with 6 chickens, you'd expect to find something as a predator would be unlikely to catch and kill 6 chickens without dropping a single feather. It's just a matter of finding where they went.