RAFAH, Gaza Strip — Hamas released two elderly Israeli women held hostage in Gaza on Monday, as the United States expressed increasing concern that the escalating Israel-Hamas war will spark a wider conflict in the region, including attacks on American troops.

The death toll in Gaza rose rapidly as Israel ramped up airstrikes, flattening residential buildings in what it says was preparation for an eventual ground assault. The U.S. advised Israel to delay an expected ground invasion to allow time to negotiate the release of more hostages taken by Hamas during its brutal incursion two weeks ago.

Small Aid Convoy Enters Gaza

A third small aid convoy from Egypt entered Gaza, where the population of 2.3 million has been running out of food, water and medicine under Israel’s two-week seal. With Israel still barring entry of fuel, the U.N. said its distribution of aid would grind to a halt within days when it can no longer fuel its trucks. Gaza hospitals flooded by a constant stream of wounded are struggling to keep generators running to power life-saving medical equipment and incubators for premature babies.

The two freed hostages, 85-year-old Yocheved Lifshitz and 79-year-old Nurit Cooper, were taken out of Gaza at the Rafah crossing into Egypt, where they were put into ambulances, according to footage shown on Egyptian TV. The two women, along with their husbands, were snatched from their homes in the kibbutz of Nir Oz near the Gaza border during Hamas’ Oct. 7 rampage into southern Israeli communities. Their husbands were not released.

Hamas said it had released them for humanitarian reasons, days after freeing an American woman and her teenage daughter. Hamas and other militants in Gaza are believed to have taken roughly 220 people, including an unconfirmed number of foreigners and dual nationals.

Israeli Ground Offensive Expected

Israel is widely expected to launch a ground offensive in Gaza, vowing to destroy Hamas. Iranian-backed fighters around the region are warning of possible escalation if that happens, including targeting U.S. forces deployed in the Mideast.

The U.S. has told Iranian-backed Hezbollah in Lebanon and other groups not to join the fight. Israel and Hezbollah have traded fire almost daily across the Israel-Lebanon border, and Israeli warplanes have struck targets in the occupied West Bank, Syria, and Lebanon in recent days.

National Security Council spokesman John Kirby said there had been an uptick in rocket and drone attacks by Iranian-backed militias on U.S. troops in Iraq and Syria, and the U.S. was “deeply concerned about the possibility for any significant escalation” in attacks in coming days.

He said U.S. officials were having “active conversations” with Israeli counterparts about the potential ramifications of escalated military action.

The U.S. advised Israeli officials that delaying a ground offensive would give Washington more time to work with regional mediators on securing the release of more hostages, according to a U.S. official.

Israeli Tanks, Troops at Gaza Border

Israeli tanks and ground forces have been massed at the Gaza border, and Defense Minister Yoav Gallant told troops there Monday to keep preparing for an offensive “because it will come.” He said it will be a combined offensive from air, land and sea but did not give a timeframe.

A ground offensive is likely to dramatically increase casualties in what is already the deadliest by far of five wars fought between Israel and Hamas since the militant seized power in Gaza in 2007.

More than 1,400 people in Israel have been killed — mostly civilians slain during the initial Hamas attack. At least 222 people were captured and dragged back to Gaza, including foreigners, the military said Monday, updating a previous figure.

More than 5,000 Palestinians, including some 2,000 minors and around 1,100 women, have been killed, the Hamas-run Health Ministry said Monday. That includes the disputed toll from an explosion at a hospital last week. The toll has climbed rapidly in recent days, with the ministry reporting 436 additional deaths in just the last 24 hours.

Israel said it had struck 320 militant targets throughout Gaza over the last 24 hours. The military says it does not target civilians, and that Palestinian militants have fired over 7,000 rockets at Israel since the start of the war.