Dead Chickens

We went down to Mandy's for dinner at 3:45pm and returned around 7:00pm. There was a dead white chicken in the neighbor's front yard. So we stopped and I threw it in the back of the truck and went to check out the rest. At that time I thought maybe it had been hit by a car, although the chickens hadn't been out front.
The setting Wyandote wasn't on her nest, and the fencing around it was bent. I went out and could count only 20 chickens. After going around the coop I located the Wyandote hiding under the play tent and round up 3 other hens that were in front of the shop. That left 2 hens still missing. I walked around the back of the shop while Steve started up the 4-wheeler. Over by the burn pile was a dead NH Red with two piles of feathers, one red and one white. I then saw the last chicken, a red, walking around rather dazed with feathers sticking-out wildly. Some dog must have gone into the coop and chased out the Wyandotte, ran after the others, attacked them by the west fence, killed the red and white, and taken the white off to the neighbor's.
Where is coop cam when we need it? And where was Bingo, she is supposed to protect the flock.
Down to 23 hens and 2 roosters. Steve was sad it wasn't at least one of the roosters - and why didn't they protect the hens?