Well the dog did not appear to be a pit bull to me at all, he looked shaggy and like a mix of some sort to me, but I couldn't tell if he perhaps had pit in him or not. He looked sad to me though... I wonder if he is grieving his pack mates .

As far as stray/abandoned dogs killing in packs, it's a common occurrence. I read and researched about it some years ago and basically the explanation is, they have the hunting instincts of the wolf pack but the domestication and play behavior of a dog. They will kill out of an instinctive hunting drive but have lost the instinct through domestication of only killing what is needed to survive. It is the same with breeding, a wolf pack only has the alpha pair breed and only one litter a year, but a dog, while he still has the instinct to reproduce does not have the instinct that tells him that he cannot provide for continual litters, he will breed and mate indiscriminately if provided the opportunity, so too with the killing/hunting in a pack with strong prey drives.

I probably didn't explain that all that well but hopefully it's understandable. I feel sad that they resorted to shooting the dogs, but I guess if they showed aggression when being taken they felt they had no choice.