United Nations Secretary-General, António Guterres condemned on Friday Israeli bombing a school serving as a shelter in Nuseirat refugee camp in Gaza strip, killing 18 people and six United Nations Relief and Works Agency for Palestine Refugees (UNRWA) staff.

"The continued lack of effective protection for civilians in Gaza is unconscionable, Civilians as well as the infrastructure they rely on must be protected and the essential needs of civilians met” Stéphane Dujarric the Spokesman for Guterres said in a statement

Guterres called on to abide by international humanitarian law at all times, and an immediate ceasefire.

UN official pointed out that this incident raises the number of UNRWA staff killed to 220 workers and it must be independently and thoroughly investigated to ensure accountability.

UNRWA said that six of its employees were killed in the Israeli bombing, including a director of a shelter and a number of members of a team providing assistance to the displaced, noting that the school had been bombed five times since the beginning of the Israeli aggression on Gaza, and it had been sheltering about 12,000 displaced persons, most of whom were women and children.