Israel 'knew building was UN shelter' - UNRWA
Israel had been informed that a building hit by shells was being used as a UN shelter before it was targeted, a UNRWA spokesman has said.
Chris Gunness of the United Nations Relief and Works Agency told the BBC that too many civilians were being killed in the "appalling conflict".
At least 13 people were killed and more than 200 injured when the UN-run school was hit the Gaza health ministry says.
Israel launched its military offensive on 8 July with the declared objective of stopping Hamas firing rockets from Gaza.