My dog recently had puppies. I recently found her with almost all of them dead and one missing. Do you think she killed them or our other dog?

I have a Walker female who had 8 healthy 4 week old puppies. She started avoiding feedeing them two days ago and snapping at them. I started trying to feed them, mushy Iams puuppy feed, the consistancy of liquid (mixed with warm water)which they ate with no problem, twice a day. They had been trying to chase her around to feed and she was not letting them nurse. This morning there wre two living, one I can't even find and the rest were dead. They were partially buried and she was laying on the ones she had partially buried. Several of them had bite marks with blood on them. I took the two living ones out, of course. None of them looked sick or acted sick in any way.These two living ones appear healthy. Do you think she killed them (and maybe even ate the other puppy)? There is another female in the kennel with them, but she has been in there with them all along with no problems?