Israel-Gaza updates: IDF says 2 hostages rescued from Gaza

The U.S. would not support Israel sending its military into the southern Gaza city of Rafah -- where many Gaza residents have fled for safety -- if Israel does not consider the impact to civilians, White House national security spokesperson John Kirby told reporters.

"More than a million Palestinians are sheltering in and around Rafah. That's where they were told to go," Kirby said. "The Israeli military has a special obligation, as they conduct operations there or anywhere else, to make sure that they're factoring in protection for civilian life -- particularly civilians that were pushed into southern Gaza by operations further north."

"Given the circumstances and the conditions there that we see right now, we think a military operation at this time would be a disaster for those people," Kirby said.

Kirby noted that the U.S. has not seen any Israeli plans "that would convince us that they are about to or imminently going to conduct any kind of major operations in Rafah."

-ABC News’ Fritz Farrow

State Department deputy spokesperson Vedant Patel acknowledged Thursday that the U.S. was aware of reports that two American citizens had been detained by the Israel Defense Forces in Gaza but said he couldn’t share anything more.

"We have no higher priority than the safety and security of American citizens overseas," Patel said. "We are aware of these reports, and we are currently seeking additional information. But I don't have any additional information to share and would not be able to at this point, given the privacy considerations."

White House national security spokesperson John Kirby told reporters, "Obviously, this is the kind of thing to take very seriously. So, we'll be talking to our Israeli counterparts and trying to get information, more context here, about what happened."

-ABC News’ Shannon Crawford

Israeli Prime Minister Benjamin Netanyahu will likely send negotiators to Cairo in the coming days, an Israeli political source told ABC News.

Egypt and Qatar are co-hosting a new round of negotiations on the proposed hostage and cease-fire deal on Thursday in Cairo, according to Egyptian state TV.

-ABC News' Jordana Miller

Aid organizations are sounding the alarm as Israeli troops advance toward Rafah, the southernmost governorate of the war-torn Gaza Strip, where more than a million people are displaced.

The Norwegian Refugee Council warned Thursday that expanded military operations on overcrowded Rafah would "lead to more civilian deaths and risk the aid system in Gaza coming to a halt."

"An expansion of hostilities could turn Rafah into a zone of bloodshed and destruction that people won't be able to escape. There is nowhere left for people to flee to," Angelita Caredda, regional director for the Middle East and North Africa at the Norwegian Refugee Council, said in a statement. "Conditions in Rafah are already dire, and a full-scale Israeli military operation will lead to even more loss of civilian life. Aid workers have been grappling with insecurity and insufficient aid for months. Attacks in areas where they provide food, water and shelter means this life-saving support will be impeded, if not entirely stopped."

"Repeated relocation orders issued by Israeli authorities over four months of hostilities have forced tens of thousands of people to flee multiple times to areas that are not safe and where shelter is not available," Caredda added. "Palestinians are being pushed into tiny corners, narrow alleys, and overcrowded shelters while residential areas continue to be pounded."

The Israel Defense Forces originally designated some of the relocation areas in Gaza as "safe zones," but they have been heavily bombarded, according to the Norwegian Refugee Council. The United Nations estimates that 67% of the coastal enclave, or 246 square kilometres, has been placed under evacuation orders amid the latest outbreak of war between Israel and Gaza's militant rulers, Hamas.

Meanwhile, the International Rescue Committee warned Wednesday that more military operations in Rafah would "significantly disrupt aid transfers from Egypt and prevent aid agencies from delivering even the most basic services to the Palestinian people who were told by Israel they would be safe there."

"More than half of Gaza's 2.2 million population are seeking refuge in Rafah, with the majority residing in temporary shelters, tents, or exposed to the elements," Bob Kitchen, vice resident of emergencies at the IRC, said in a statement. "Within the last 48 hours, airstrikes on residential zones in Rafah have killed at least 11 Palestinians, two of them children. If Israel expands its operations further south, it would mean the renewed forced displacement of more than a million people who have nowhere left to go; and it would end the humanitarian lifeline from Egypt."

"If they aren't killed in the fighting, Palestinian children, women and men will be at risk of dying by starvation or disease," Kitchen added. "There will no longer be a single 'safe' area for Palestinians to go to as their homes, markets, and health services have been annihilated."

Both the IRC and the Norwegian Refugee Council are calling for the warring sides to agree to an immediate cease-fire.

-ABC News' Zoe Magee and Morgan Winsor