Those who died are the Holy Innocents. The church, in its wisdom, has seen fit to saint all those innocent lives that were sacrificed in an attempt to kill the baby Jesus... Herod obviously didn't know that Jesus and his parents had fled to Egypt.
There isn't anything worse that a parent can experience than the death of their own children... at any age. Parents are not supposed to bury their kids... and yet so many do. Thanks be to God that it isn't often that they are brutally murdered as the Holy Innocents were, but burying one's child is a loss that is so difficult to suffer and one that a person never gets over.
I remember attending a funeral of a baby who died 1 hour after childbirth. The mother had been on bedrest for months and yet the baby died anyway. The family and everyone who knew them was absolutely devastated. When the preacher stood in the pulpit to begin his sermon I kept thinking "what can he possibly say? where is the good news?" And, to my surprise, he came up with something...
He talked about the struggle the family had - the bed rest, the time apart, the prayers the support that everyone had given to bring this child into the world. He thanked God for the short time the parents had to hold the baby and tell him that he was loved. He went on to remind us that life is eternal and while we are devastated to have had lost this child, the good news was that his life would only know joy. That he would only know the love of God, that he was surrounded by family members that had gone before him and that his life would never know disappointment or rejection or failure. He would only know joy. That is the comfort.
We can't imagine the horror of those parents of the Holy Innocents centuries ago, but we certainly remember that they suffered. We also stand with those who have lost children since with the comfort of knowing that while they are missed, those children are with God and only know joy.