Gaza City and surrounding areas are officially suffering from famine, and it will likely spread, a global hunger monitor determined on Friday, an assessment that will escalate pressure on Israel to allow more aid into the Palestinian territory.

Hospital officials in Gaza say Israeli strikes and gunfire have killed at least 33 Palestinians sheltering in tents or seeking scarce food aid.

For an area to be experiencing famine, at least 30 percent of children under 5 must be considered acutely malnourished by height and weight measures. Using the arm circumference method, the I.P.C. said, the accepted threshold dropped to 15 percent.

A drone attack on a U.N. convoy set fire to all 16 trucks carrying desperately needed food to Sudan’s famine-hit North Darfur region and destroyed all the vehicles, the United Nations said Thursday.