The word "innocence", incorporating the Latin verb nocere (to harm), means "doing no harm". It's a far stronger notion than mere harmlessness. The state of innocence evokes a total incapacity for hurting one's fellow men. Although my knowledge of Judaism is superficial, and regardless of the fact that I consider all Bible-based religions as a bunch of myths and legends, I would imagine that young Jewish students of the the Tanach and Rabbinic literature are particularly innocent individuals, in the sense I've just defined, because Judaism is an immensely humanistic philosophy, and its adepts have an unbounded respect for all the planet's men, women and children. Normally, a fellow who decides to enroll in a yeshiva to study these ethereal subjects in depth, maybe with a view to becoming a rabbi, can have no place in his heart for hatred.
The Hebrew word Mercaz means "center", and HaRav is literally "the rabbi". Many Israelis think of the Mercaz HaRav yeshiva in Jerusalem, founded in 1924 by the great Zionist rabbi Avraham Kook, as the national yeshiva of the modern state of Israel. The Palestinian terrorist who selected this place to vent his hatred was probably aware of its prominent status... or maybe he simply decided to strike this school because he happened to be employed there as a chauffeur.
Eight students died and nine were wounded before the terrorist was killed.
In Gaza, certain people danced with joy when they heard of this attack, and Hamas authorities said: "We bless the operation." In that trite declaration, I'm curious to know the meaning, if any, of the verb "bless". One thing is certain: it has nothing to do with innocence.