My baby bunnies of 5 month died today?

i am hear breaked i had 5 bunnies 2 got adopted and i had keept 3 more for me they were fine 2 hours ago when i saw that 2 died my baby frncesca and my baby sleppy i don't know if there mother can hurt them i did not find any marks on them and my mum told me she had feed them at 8 am my time zone when i went to pet them and kiss them i saw them there.now i am in pain and i fell like the earth has colapsed one me .can somebody tell me can the salat food afect him and why did they die.tk u