I had a group of mice together and the agouti female got pregnant right around the time the other female was already giving birth. Well she had her litter sometime last night or this morning and she killed all the babies. I'm not sure how many there were because she literally left them in pieces. Some pinkies had their heads chewed off, some had paws chewed off, etc. She was fine around the other female's litter when they were born. I'm not sure why she would destroy her own litter like this. They have plenty of water (I check the sipper every time I refresh their water) and they had tons of food. I wasn't messing with them yesterday or this morning other than refreshing water.