United Nations Secretary-General Ban Ki-moon condemned Israel for firing on seven UN schools during last year’s war in Gaza, killing Palestinians who had sought shelter there.

“I deplore the fact that at least 44 Palestinians were killed as a result of Israeli actions and at least 227 injured at United Nations premises being used as emergency shelters,” Ban wrote in a letter to the Security Council, summarizing the findings of an independent UN board of inquiry.

Ban set up the five-member panel in November to investigate attacks that damaged at least 223 schools and facilities that were run by the UN or Hamas, which rules the Gaza strip, during the seven-week conflict there last summer.

More than 2,100 Palestinians and 70 Israelis were killed after fighting ended in a truce in August.