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(CNN) – The United Nations says this is the sixth time one of its schools, now used to shelter thousands of Palestinians, has taken a direct hit in the conflict in Gaza. Officials do not call these "attacks" on their compounds because, they say, that would suggest purposeful targeting.
Either way, the UN teams trying to help these people call the latest incident "a breaking point."
But who should be held responsible?
U.N. Relief and Works Agency Spokesman Christopher Gunness reserves blame for both sides.
"We condemn in the strongest possible terms this particular incident which was a serious violation of international law, but we condemn the other side, as well, when they have committed violations against us such as placing rockets in our schools and we again call on the warring parties to respect the sanctity of civilian life, the property and to respect their obligations to protect humanitarian workers under international humanitarian law," Gunness told CNN's Jake Tapper.
In at least three times in two weeks rockets have been found in a U.N. School, according to the organization itself. Israeli officials allege that is the work of Hamas.
Israel has not claimed responsibility for the shelling, but its military did admit that a group of militants fired at Israeli soldiers from the area of the school and those soldiers returned fire.
Gunness is adamant that is not justification for retaliation under international law.
"If there is an intention to attack a U.N.-designated school, with a clearly marked U.N. blue flag on top of it... then there are certain procedures to follow," says Gunness. "You can't just strike it because you think there are militants nearby, but as I say, there are questions about proportionality. There are questions about distinction between combats and non-combatants and I suggest you put that to the Israeli army because our initial investigation found it was Israeli artillery that struck the school."
For more of our interview with the U.N. spokesman, watch the video above.