Kitten Missing! Cat Den Raided Attacked By A Wild Animal!

READ THIS: i went over to see the kittens and only 3 were in the den and very scared. all 4 kittens there the day before, but the mother was nowhere to be seen... did one die and the mother was burying it? the kittens clung to me and refused to stay in the den whilst i wondered what may have happened for there to be only 3 kittens, and not 4. i was there for about 5 minutes when suddenly the mother appeared from inside then den.... and of course i wondered where she came from so i took a look around the side... omg! there it was... a massive hole dug into the rear of the den by an obviously determined foe! what could it be that would dig such a hole? it must have been a harrowing night for the kittens, and the mother must've fought courageously for their lives... seems the frontal attack was no good and the mother much too fierce and aggressive coz it's quite a big opening to defend. after inspecting the mother for injuries i found none, nor any evidence she dug the hole.