The United States has deployed a second aircraft carrier to the Mediterranean “to deter hostile actions against Israel or any efforts toward widening this war”, as residents of Gaza City fled south to escape an expected Israeli ground attack in response to a murderous rampage by Hamas last weekend that left at least 1,300 people dead. The US defence secretary, Lloyd Austin, said late on Saturday that the presence of the USS Eisenhower and its affiliated warships in the eastern Mediterranean signalled Washington’s “ironclad commitment to Israel’s security and our resolve to deter any state or non-state actor seeking to escalate this war”. The White House national security adviser, Jake Sullivan, warned against a new front on the Israel-Lebanon frontier and added: “We can’t rule out that Iran would choose to get directly engaged some way. We have to prepare for every possible contingency.” Iran is a long-time backer of Hamas and also Hezbollah in Lebanon, which has exchanged fire with Israel over the past few days. “That is a risk and that’s a risk that we have been mindful of since the start,” he told CBS news. “It’s why the president moves so rapidly and decisively to get an aircraft carrier into the eastern Mediterranean … a very clear message to any state or any actor that would seek to exploit this situation.” The Iranian foreign minister, Hossein Amir-Abdollahian, was quoted by the semi-official Fars news agency on Sunday as saying “the hands of all parties in the region are on the trigger” if Israel does not end its “aggressions”. The Palestinian health ministry said 2,670 people had been killed and more than 9,600 wounded in Gaza, surpassing in one week the numbers killed by Israeli bombardments over a period of six weeks in 2014. “The situation is unprecedented. I’m not even going to call it a humanitarian crisis. It’s one of humanitarian collapse,” said an international aid worker based in Gaza, who said they wanted to sound the alarm but asked not to be named. The Israeli Defence Forces (IDF) reiterated calls for civilians to move south of the Gaza River, demanding the displacement of an estimated 1.1 million people. The Israeli military said hundreds of thousands of Palestinians had headed south so far, and that a third road had been identified as a “safe route” on Sunday. Some who had fled south of the Gaza River described such poor conditions that they knew others who had gone back to Gaza City. “The overcrowding is really bad. It’s common for people to be sleeping 20 or 30 to a room, the humanitarian needs are dire,” said the aid worker. “The most shattering thing about this is that we are just at the beginning, and the situation is about to get a lot worse.” In Gaza City, Mahmoud Shalabi, a humanitarian coordinator with Medical Aid for Palestinians, said the situation was untenable. “Last night, half of it was calm for the first time and the other half was really violent and severe. Again, all places across the Gaza Strip were hit hard, houses were destroyed on top of families sleeping inside,” he said. “I’m talking about everywhere in Gaza. Again, we are debunking the myth of this safe place in the southern part of Gaza,. “Palestinians are still trying to get basic commodities, like food,” he said, describing how he had been unable to find bread for his family at the few bakeries that have remained open. “Even the big supermarkets aren’t open, because according to the suppliers who still have some quantities of food they are afraid of moving their trucks to distribute to any of the shops in the neighbourhood. They’re asking supermarket owners to go there and get whatever they can for their shops,” he said. Despite the bombardments and growing fears of a ground invasion, some said they were reluctant to move south, fearing they would never be able to return to their homes. According to the UN, on at least three separate occasions in the last 48 hours, fleeing civilians have been hit by rocket fire, leaving some also to fear they will be killed if they try to move south. The world body has said Israel’s order to evacuate the northern end of the territory is “logistically impossible” in a short period of time. In Israel, orders were given on Sunday to completely evacuate the town of Sderot, less than a mile from Gaza, by nightfall. The Israeli prime minister, Benjamin Netanyahu, convened the first meeting of Israel’s expanded emergency cabinet at a military headquarters in Tel Aviv for the first time on Sunday. The unity “war cabinet” includes the opposition lawmaker, retired army general and former deputy prime minister Benny Gantz and the defence minister, Yoav Gallant. “Hamas thought we would be demolished. It is we who will demolish Hamas,” Netanyahu said. The US president, Joe Biden, spoke to Netanyahu on the phone on Saturday and “affirmed his support for all efforts to protect civilians”, the White House said in a statementthat did not specifically mention Gaza. Biden also spoke to the Palestinian Authority’s leader, Mahmoud Abbas, for the first time since hostilities broke out a week ago. “Hamas does not stand for the Palestinian people’s right to dignity and self-determination,” Biden told Abbas, according to a White House statement. Biden in the call also pledged “full support” to the Palestinian Authority in its efforts to bring humanitarian assistance to Palestinians, “particularly in Gaza”, the statement said. Israel’s energy minister, Israel Katz, said the country would renew some water supplies to areas in the southern Gaza Strip, after an agreement between Netanyahu and Biden. He said the decision was in line with Israeli policy to tighten the 16-year blockade of the territory. The UN agency for Palestinian refugees (UNWRA) said it could not confirm whether water had been restored. The World Health Organization (WHO) has condemned Israel’s order to evacuate 22 hospitals in northern Gaza that are treating more than 2,000 inpatients. The organisation said the evacuation “could be tantamount to a death sentence” for patients who include newborns in incubators and people in intensive care. “The lives of many critically ill and fragile patients hang in the balance,” it said. Two hospitals said they had received instructions from the Israeli military to evacuate on Sunday under threat of bombardment. The Palestinian news agency Wafa said that this included the Kuwaiti hospital in Rafah at the southern end of the strip. Hospital administrators had refused the evacuation order because of the number of patients in critical condition who “would face an imminent risk of death,” it said. Aid flights have been arriving in Egypt’s Sinai peninsula with relief supplies for Gaza, amid diplomatic efforts to open humanitarian corridors into the territory. The US secretary of state, Antony Blinken, said during a tour of the region that the US was seeking agreement on establishing aid routes and safe zones, though there were few outward signs of success. Blinken is expected to return to Israel on Monday for further consultations. Egypt controls the Rafah border crossing into Gaza, but under an agreement between Israel and Egypt after Hamas seized full control of Gaza in 2007, supplies entering from the south require Israeli approval. Since the Hamas attack last Saturday, Israel has cut off electricity and water to the territory, actions the UN considers war crimes. Negotiations have been taking place to open Rafah to foreign and dual nationals fleeing Gaza, but the crossing remained shut as of Sunday afternoon, with few indications it might open soon. Blinken said he was also trying to ensure the conflict did not spread.