He called the attack "unjustifiable" while speaking with reporters upon his arrival in Costa Rica. In addition to condemning the attack, Ban made it clear that the Israeli military knew the location of the school and that Palestinian civilians were told to seek shelter there.
"Nothing is more shameful than attacking sleeping children. At least 16 civilians are dead and many more are injured. I want to make it clear that the precise location of this Jabalia Elementary Girls School had been communicated to the Israeli military authorities 17 times -- as recently as last night, just a few hours before the attack. They were aware of the coordinates and exact locations where these people are being sheltered."
Other U.N. sites have been designated as shelters and they, too, have been repeatedly shelled.
"I condemn this attack in the strongest possible terms. It is outrageous. It is unjustifiable. And it demands accountability and justice," he said.
Ban called for Israel to better guarantee the safety of Palestinian civilians who are seeking shelter from the attacks on Gaza. He also renewed the demand for an immediate and unconditional cease-fire.