A stampede at a food distribution site run by an Israeli-backed American organization in the Gaza Strip killed 20 Palestinians on Wednesday, the group said, in the first acknowledgment of deadly violence at its operations.

Israel’s air and ground war has destroyed vast areas of Gaza and driven some 90% of the population from their homes. Aid groups say they have struggled to bring in food and other assistance because of Israeli military restrictions and the breakdown of law and order, and experts have warned of famine.