Israel's military campaign since has killed nearly 55,000 Palestinians, most of them civilians, according to health authorities in Gaza, and flattened much of the densely populated strip. Most of the population is displaced, and widespread malnutrition is a significant concern.

The UN human rights chief said Israel's "means and methods of warfare" were inflicting "horrifying, unconscionable suffering".

Survivors from one of the shootings said Israeli forces began firing on the crowd of hungry Palestinians in the pre-dawn hours.