Israeli airstrikes hit a school being used by displaced Palestinians in central Gaza on Saturday, killing at least 30 people, as the country’s negotiators prepared to meet international mediators to discuss a proposed cease-fire.

At least one small child was among the dead taken from the girls’ school in Deir al-Balah to Al Aqsa Hospital. Israel’s military said it targeted a Hamas command center used to direct and plan attacks against Israeli troops and develop and store “large quantities of weapons.” Hamas in a statement called the Israeli military’s claim false.

Civil defense workers in Gaza said thousands had been sheltering in the school, which also contained a medical site.

Associated Press journalists saw a dead toddler in an ambulance and bodies covered with blankets. Inside the school, shattered walls gaped and classrooms were in ruins. People searched for victims in rubble strewn with pillows and other signs of habitation.