KHAN YOUNIS, Gaza Strip >> Israel pounded the Gaza Strip with airstrikes Thursday, including in the south where Palestinians were told to take refuge, and the country’s defense minister ordered ground troops to “be ready” to invade, though he didn’t say when.

Gaza’s overwhelmed hospitals tried to stretch out ebbing medical supplies and fuel for generators, as authorities worked out logistics for an aid delivery from Egypt. Doctors in darkened wards across Gaza performed surgeries by the light of mobile phones and used vinegar to treat infected wounds.

Meanwhile, an unclassified U.S. intelligence assessment delivered to Congress estimated casualties in an explosion at a Gaza City hospital this week on the “low end” of 100 to 300 deaths. The death toll “still reflects a staggering loss of life,” U.S. intelligence officials said in the report, seen by The Associated Press. It said intelligence officials were still assessing the evidence and their casualty estimate may evolve.

President Joe Biden and other U.S. officials already have said that U.S. intelligence officials believe the explosion at al-Ahli Hospital was not caused by an Israeli airstrike. Thursday’s findings echoed that.

The Israeli military has relentlessly attacked Gaza in retaliation for the devastating Oct. 7 Hamas rampage in southern Israel. Even after Israel told Palestinians to evacuate the north of Gaza and flee south, strikes extended across the territory, heightening fears among the territory’s 2.3 million people that nowhere was safe.

Palestinian militants fired rockets into Israel from Gaza and Lebanon, and tensions flared in the Israeli-occupied West Bank.

In a fiery speech to Israeli infantry soldiers on the Gaza border, Defense Minister Yoav Gallant urged the forces to “get organized, be ready” to move in. Israel has massed tens of thousands of troops along the border.

“Whoever sees Gaza from afar now, will see it from the inside,” he said. “It might take a week, a month, two months until we destroy them,” he added, referring to Hamas.

Israel’s consent for Egypt to let in food, water and medicine provided the first possible opening in its seal of the territory. Many Gaza residents are down to one meal a day and drinking dirty water.

Egypt and Israel were still negotiating the entry of fuel for hospitals. Israeli military spokesman Rear Adm. Daniel Hagari said Hamas has stolen fuel from U.N. facilities and Israel wanted assurances this won’t happen. The first trucks of aid were expected to go in Friday, Egypt’s state-owned Al-Qahera news reported.