A disabled Palestinian lies on seats after being evacuated from a U.N-run school sheltering Palestinian refugees, which witnesses said was hit by Israeli shelling, at a hospital in the northern Gaza Strip July 24, 2014. At least 15 people were killed and many wounded on Thursday when Israeli forces shelled a U.N.-run school sheltering Palestinian refugees in northern Gaza, said a spokesman for the Gaza health ministry, Ashraf al-Qidra.(Photo:Reuters)

A Palestinian boys closes the gate of a United Nations school where hundreds of families sought refuge after fleeing their homes due to heavy Israeli missile strikes in Gaza City, Wednesday, July 23, 2014. (AP Photo)

A Palestinian boy cries after being evacuated from a U.N-run school sheltering Palestinian refugees, which witnesses said was hit by Israeli shelling, at a hospital in the northern Gaza Strip July 24, 2014. (Photo:Reuters)

A Palestinian rests on the ground at a United Nations school where hundreds of families sought refuge after fleeing their homes due to heavy Israeli missile strikes in Gaza City, Wednesday, July 23, 2014. (AP Photo)

Relatives of Palestinians, whom medics said were killed in Israeli shelling at a U.N-run school sheltering Palestinian refugees, mourn outside a hospital morgue in the northern Gaza Strip July 24, 2014. (Photo:Reuters)

Relatives of Palestinians whom medics said were killed in Israeli shelling at a U.N-run school sheltering Palestinian refugees, mourn outside a hospital morgue in the northern Gaza Strip July 24, 2014. (Photo:Reuters)

A Palestinian mother comforts her child in a hospital a few hundred meters from where medics said Israeli shelling hit a U.N-run school sheltering Palestinian refugees, in Beit Hanoun the northern Gaza Strip July 24, 2014.(Photo:Reuters)

A Palestinian mother comforts her child after what medics said was an Israeli shell that hit a U.N-run school sheltering Palestinian refugees, at a hospital in Jabaliya in the northern Gaza Strip July 24, 2014. (Photo:Reuters)

A Palestinian girl, whom medics said was wounded in Israeli shelling at a U.N-run school sheltering Palestinian refugees, lies on a bed at a hospital in the northern Gaza Strip July 24, 2014. (Photo:Reuters)