The 27 people killed at the school were among at least 100 Palestinians left dead in Israeli strikes across the Gaza Strip on Thursday, according to Palestinian medical authorities.
Israel has announced a major expansion of military operations in the Gaza Strip, saying large areas of the enclave would be seized and added to its security zones while certain areas would be cleared.
There are fresh hopes for a ceasefire in Gaza after Hamas accepted a proposal from mediators that includes the release of five Israeli hostages each week.
Israeli defence minister Israel Katz says if Hamas continues its refusal to free hostages, Israel will take territory and make sure it is completely defeated.
As Palestine's health authorities put the Gaza death toll at over 50,000, Hamas says Israel's latest strike has killed a political leader Salah al-Bardaweel.
As Hamas contemplates the latest ceasefire proposal by the US, Israel is ramping up attacks in Gaza in a bid to pressure them to release the remaining hostages.
Israelis have protested in front Prime Minister Benjamin Netanyahu's office, against a move to sack the head of the Shin Bet domestic security service.
Israel’s latest military escalations have killed almost 600 Palestinians across Gaza since Tuesday, with the IDF celebrating the elimination of Hamas leaders as ground and air operations continue.