This incident has the potential to become Cast Lead's Qana: a humanitarian disaster, caused by the use of human shields, that leads the international community to force Israel into a ceasefire. It turns out that the Palestinians have been using that school as a mortar launching pad for years...

... and that's what happened this time. That and a bunch of secondary explosions from the weapons they were storing inside:

Schools, hospitals, and holy places - three locations that are supposed to be sacrosanct and off-limits according to all civilized laws of warfare. Hamas already had the hospitals and mosques covered. Now the educational facilities that terrorists had long ago tangled up with weapons production and storage.

References:
* Hamas: We Will Murder Jewish Children All Over The World (Plus: Diplomats Trying To Stop The IDF From Winning) [MR]
* US urges restraint after Qana but no ceasefire [Reuters]
* UN School Used by Terrorists As a Weapons Dump [LGF]
* Gaza Hospitals Overflowing With Hamas Weapons, Palestinian Vigilante Murder [MR]
* Hamas's Militarized Mosques Not Immune From Israeli Jets [MR]
* UN Schools Notorious for Shielding Terrorists [LGF]

Previously:
* Video: Hamas Brags About Using Women And Children As Human Shields
* Video: Hamas Prepares Army Of Women And Children To Be Suicide Bombers During Urban Warfare
* Hamas Forcing Civilians To Stand On Roofs They Know Are About To Be Hit