Global news agencies have decried the Israel Defense Forces strike near a United Nations school in Gaza on Tuesday, in which dozens were killed, and Palestinian sources said the casualties were mostly civilians.

The Israeli army, however, claimed that terrorists were firing mortar shells from the school just moments before the strike. The IDF stated that a number of Hamas gunmen were inside the school, among them Imad and Hassan Abu-Askar, who are known to the IDF as Hamas operatives.

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According to the Palestinian reports, a number of tank shells landed around the school, in which refugees who had fled their nearby homes were taking shelter.

Reports are unclear regarding the precise number of casualties, but Palestinian sources said many of the dozens killed were women and children. They added that the number may still rise, as many of the wounded suffer life-threatening injuries.

It was the second UNRWA school to be hit Tuesday. Earlier, three civilians were killed in a strike on a Khan Younis school in which refugees had gathered.

An additional 13 civilians were killed in an earlier IDF strike that leveled a four-storey structure in Gaza City's Zeitoun neighborhood.

Rescue teams were searching for more bodies and survivors under the rubble. During the evacuation of the injured, a second structure was hit in the neighborhood.