“People are facing the immediate possibility of starvation,” said Abeer Etefa, a Mideast regional spokeswoman for the U.N.’s World Food Program.
The Israeli prime minister’s comments come as the Palestinian death toll soars over 11,000.
“Much more needs to be done to protect civilians and to make sure that humanitarian assistance reaches them,” U.S. Secretary of State Antony Blinken said.
More than two-thirds of Gaza’s population of 2.3 million have fled their homes since the war began.
Two strikes hit a U.N. school-turned-shelter just north of Gaza City, killing several people in tents in the schoolyard and women who were baking bread inside the building.
“Many people are relying on brackish or saline ground water, if at all,” said U.N. deputy Mideast coordinator Lynn Hastings.
“This debacle will be investigated. Everyone will have to give answers, including me,” Netanyahu said, two and half weeks after the attack.
With no end in sight after nearly four weeks of war, U.S. and Arab leaders raised pressure on Israel to ease its siege and at least briefly halt its attacks.
The toll from Tuesday’s strikes was also unknown, though the director of a nearby hospital said hundreds were killed or wounded.
Internet and phone services collapsed in the Gaza Strip under intensified Israeli bombardment Friday night.