Vital humanitarian aid is piling up at the shuttered Gaza border, despite diplomatic efforts to open a corridor with Egypt, as the World Health Organization warned that water is running out for hundreds of thousands of displaced Palestinians in the bombarded territory. Gaza has been under siege by Israel for for more than a week, in response to the deadly incursion by Hamas, the Islamist militant group that controls the coastal enclave, home to 2.2 million people. Some are gathering at the Rafah crossing between Egypt and Gaza hoping to leave, as critical supplies like fuel, food and water run short, leaving hospitals on the brink of collapse and families facing dehydration and starvation. Amid growing international pressure to address the humanitarian crisis, United States President Joe Biden will travel to Israel on Wednesday, an extraordinary wartime visit that follows frenzied efforts by Secretary of State Antony Blinken across the Middle East – including a seven-hour negotiation session with top Israeli officials. On Tuesday, Blinken announced that the US and Israel "have agreed to develop a plan that will enable humanitarian aid from donor nations and multilateral organizations to reach civilians in Gaza." However, it is unclear if any progress was made on the opening of the Rafah crossing, the only entry point to Gaza not controlled by Israel. A Palestinian border official told CNN on Saturday that concrete slabs had been placed at the crossing, blocking all gates. Egypt, meanwhile, claims that Israeli airstrikes on the Gaza side of the border have made roads inoperable. Water warnings Urgent calls for help are growing on both sides of the border. On the Egyptian side, United Nations teams are waiting at the Rafah crossing, hoping they will be given the green light to enter Gaza and open a humanitarian corridor. In a social media post Monday, the World Health Organization (WHO) warned that Gaza faces an "imminent" public health crisis, with water running out and the lives of more than 3,500 patients in 35 hospitals at immediate risk. WHO spokesperson Margaret Harris told CNN the UN health agency had struck an agreement with Egypt's president to open the Rafah crossing for aid – but Israel's strikes rendered the facility unsafe, thereby halting the movement of crucial supplies. "It's a terrifying, really distressing waiting game, with all of us only wanting to help," Harris said, adding there are about 84,000 pregnant women in Gaza, with many delivering every day. "Babies don't care about bombs, they come when they come," she said. UN humanitarian envoy Martin Griffiths is expected to travel to Cairo on Tuesday to aid diplomatic efforts, according to a release from the UN Office for the Coordination of Humanitarian Affairs. His trip will include a visit to Israel. A convoy of trucks carrying aid supplies was traveling through Egypt toward the crossing early Tuesday, according to state-affiliated media outlet Al-Qahera News. Much of the aid already arrived days ago, sent by multiple countries and international organizations. And on the Gaza side, large numbers of evacuees have gathered by the crossing, part of the mass migration that has seen at least 1 million people flee their homes in the past week alone, according to the United Nations Relief and Works Agency (UNRWA). One family of five Palestinian-Americans, all US citizens, drove to Rafah on Monday after hearing the borders would be opened, said Haifa Kaoud, whose husband Hesham is among the five stuck in Gaza. "They drove down to Rafah on Monday and waited for hours, but it never opened," she said, adding: "They don't have much electricity or internet access, so they depend on us for information." The family had been visiting relatives in Gaza when the war broke out; now, their loved ones in the US are desperately trying to find ways to bring them home. "The water is not clean and even though they still have food, they make sure not to eat too much so there's enough for everyone," Haifa said. "One of the brothers also takes heart medication and they're concerned about that lasting too." UNRWA said Tuesday that Gaza's last seawater desalination plant had shut down, bringing the risk of further deaths. The UN agency added that one line of water was opened for three hours in southern Gaza on Monday, serving just half the 100,000 population of Khan Younis. "Dehydration and waterborne diseases loom large, given the collapse of water and sanitation services," UNRWA said. Rising death toll On Monday, the UN Security Council rejected a Russian resolution calling for a humanitarian ceasefire because it did not get the minimum number of votes needed. Several countries including the US, the United Kingdom and France voted against it because the draft did not condemn Hamas for the October 7 attack, which the Israel Defense Forces (IDF) said left at least 1,400 people killed and scores taken hostage. The week of Israeli bombardment has killed more than 2,800 people, including hundreds of children, and wounded more than 11,000 in Gaza, Palestinian Prime Minister Mohammad Shtayyeh said on Monday, according to the official Palestinian press agency, WAFA. The director of Gaza hospitals, Dr. Mohammad Zaqout, told CNN on Tuesday morning that since midnight hospitals had received 110 bodies from different areas of south Gaza. Zaqout said 40 bodies had been received at al Nasser hospital, while 60 victims of air strikes in Rafah had been received at al Najar hospital. Another ten bodies had arrived at the European hospital. He said the bodies included some who rescue crews were able to extract from underneath the rubble of houses. "There are many more under the rubble in addition to the body parts that we cannot identify," Zarqat told CNN. "Remember these houses were hosting families who fled the north of Gaza...and took shelter with family members or people who they know," he said. Zaqout said that there 150 people in one house. "We are expecting the number of dead to increase significantly," he said. The Palestinian Interior Ministry said Israeli airstrikes had killed at least 49 people in strikes on the southern Gaza cities of Rafah and Khan Younis. IDF spokesperson Lt. Col. Jonathan Conricus told CNN he was "not aware of any strikes specifically in those areas but they could have happened." "The combat operations continue," he said. "We continue to hunt Hamas operatives to attempt to degrade their military capabilities." Israel's ambassador to the UN, Gilad Erdan, also pushed back against accusations of ethnic cleansing by a UN official who focuses on Palestinian rights. Erdan called the claims "utterly false," accusing UN Special Rapporteur Francesca Albanese of antisemitism. In a statement Saturday, Albanese accused Israel of carrying out "mass ethnic cleansing of Palestinians under the fog of war," pointing to hundreds of thousands of Palestinians previously expelled or forced to flee their homes during conflicts in 1948 and 1967. Meanwhile, several people were injured after Israel shelled Lebanese border towns on Tuesday, Lebanese state-run news agency NNA said Tuesday. Houses in al-Duheira were struck and flares were fired over Ras al-Naqoura, NNA said. Israeli shelling on areas along the Blue Line – the demarcation line between Lebanon, Israel and the Golan Heights – in the western part of the country, continued past midnight targeting civilians, it added. On Monday, two houses in al-Duheira were damaged and caught on fire due to the shelling, the agency said. — CNN