We have fishercats. They are also very vicious and have lots of sharp teeth and claws. They make a horrid call when they make a kill, sounds like I'd imagine a banshee would sound.
They look like black weasels, and are very elusive. I have only seen dead ones on the road and stuffed ones. Your stoats remind me of the fishercats around the New England area, only not black.
We have had a few attacks the last few nights, and caught a racoon on camera. I think it may be the racoon, but I wouldn't be surprised to find fishercats and fox also involved...
Ericka in Massachusetts.