Why didn't the Rosary protect her?

I have a strong devotion to the Rosary. The second promise of the Rosary is that the Blessed Mother promises her special protection. On ABC World News they reported that one of the little girls killed in the Newtown tragedy was just learning to pray the Rosary and was leading her family in prayer. Why then wasn't the little girl protected?

I would appreciate your thoughts. Thank you.

Therese