The weaponry used in the assault on Gaza caused amputations and maiming, she added. “This happened before the eyes of children,” she said. “They have seen their friends and their parents die.”

The United Nations and other humanitarian agencies are at the limit of their ability to cope with the fallout from the assault, which Ms. Ironside said had far surpassed the combined impact of two previous conflicts, in 2008-09 and in 2012. About 270,000 people have sought shelter at around 90 centers run by the United Nations Relief and Works Agency, and at least 200,000 others have taken refuge with family members, friends or neighbors.