"In the 12 days of Israel's war on Gaza, the shelling of a United Nations school on Tuesday has been the most shocking incident. More than 40 people were killed. Israel claims the school was a legitimate target because rockets were fired from it. But the UN has vehemently denied those claims.
Al Jazeera is the only international news channel with correspondents on both sides of the border. Ayman Mohyeldin visited what's left of the school, and the families now in mourning."