The United Nations said Israeli forces killed the people as they were trying to aid injured civilians, then buried them in a mass grave. Israel said nine of the 15 dead were Palestinian militants.

DEIR AL BALAH, Gaza Strip (AP) — An Israeli airstrike on Thursday killed at least 27 Palestinians sheltering at a school in northern Gaza and wounded 70 more, said Health Ministry spokesman Zaher al-Wahidi, as Israeli forces have expanded their strikes and evacuation orders across the war-torn territory in recent days.

Israel has killed at least 112 Palestinians over the past day, including dozens of children and elders slaughtered in three separate attacks on schools where hundreds of displaced families took shelter.

Israel announced a major expansion of military operations in Gaza on Wednesday, saying large areas of the enclave would be seized and added to its security zones, accompanied by large-scale evacuations of the population.

Prime Minister Benjamin Netanyahu said Israel had seized a corridor of land that would split one of Gaza’s largest cities from the rest of the enclave.

Prime Minister Benjamin Netanyahu says Israel is establishing a new security corridor across the Gaza Strip to pressure Hamas.