Amongst the seriously wounded were children.
The hospital scenes were chaotic, with some of the injured lying on the floors and grieving Palestinian families filling the corridors.
One of the survivors reported that the strikes occurred without any prior warning.
Hamas has condemned the Israeli attack on Hamama School, which was sheltering thousands of internally displaced Palestinians.
“The occupation’s criminal attack on Hamama School, which shelters thousands of displaced persons, is an insistence on the brutal war of extermination,” the group stated.
“The occupation army continues its lies by claiming that civilian sites, including schools, hospitals, and displacement centres, are being used for military purposes.”
“The occupation army uses these lies as a pretext to target defenceless civilians in Gaza,” Hamas added.
In the occupied West Bank, two Israeli attacks killed nine fighters, including a local Hamas commander on Saturday.
The latest attacks came as a high-level Israeli delegation made a brief visit to Cairo on Saturday in an attempt to resume Gaza ceasefire negotiations, Egyptian airport authority sources said.
The delegation returned to Israel hours later, Israeli media said.
Chances of a breakthrough appear low as regional tension has soared following the assassination of Hamas’s leader Ismail Haniyeh in Tehran on Wednesday, a day after an Israeli strike in Beirut killed Fuad Shukr, a top military commander from Lebanese armed group Hezbollah, a Hamas ally.
