Israel vowed to escalate its response to an attack by the Palestinian group Hamas with a ground offensive, while US President Joe Biden pledged support for Israel and issued a warning to anyone who might seek to take advantage of the situation. Israel said dozens of its fighter jets struck more than 200 targets overnight on Wednesday in a neighbourhood of Gaza City that it claimed had been used by Hamas to launch its unprecedented wave of attacks. Gaza’s health ministry said at least 1,055 people have been killed and 5,184 injured in the crowded coastal enclave. Israel’s military said the death toll in Israel had reached 1,200 and more than 2,700 people had been wounded. “We have sustained extremely heavy casualties,” military spokesperson Lieutenant Colonel Jonathan Conricus said in a video briefing on X, formerly known as Twitter. Israeli Defence Minister Yoav Gallant, speaking to soldiers near the Gaza fence, said: “Hamas wanted a change and it will get one. What was in Gaza will no longer be.” “We started the offensive from the air, later on we will also come from the ground. We’ve been controlling the area since Day 2 and we are on the offensive. It will only intensify.” At least 1,000 fighters who had infiltrated from Gaza had been killed, the Israel Hayom newspaper claimed. Israel withdrew troops from Gaza in 2005 after 38 years of occupation, and has kept it under blockade since Hamas came to power there in 2007. Israel has imposed what it called a “complete siege” on the already blockaded Gaza Strip, cutting off food, water, fuel and electricity — a move that UN Secretary-General Antonio Guterres warned would worsen an already dire humanitarian situation. On Israel’s northern border, a salvo of rockets was fired from southern Lebanon towards Israel, prompting Israeli shelling in return, three security sources said. More shells launched from Syrian territory landed in open areas in Israel, further raising fears that the violence could lead to a wider war. “We do not yet know if these rockets were fired by the Syrian armed forces, by any of the many Iranian militias that exist and are welcomed by the Syrian regime, or Hezbollah or any other action,” said Israel’s Lieutenant Colonel Conricus. “What we do know is that we retaliated fire toward the sources of fire, and currently the situation there is quiet.” Sirens warning of incoming rocket fire blared overnight in Israeli communities near the Gaza border. Over 260,000 people have been forced to flee their homes in the Gaza Strip, as heavy Israeli bombardments from the air, land and sea continue to hit the Palestinian enclave, the United Nations said. “Over 263,934 people in Gaza are believed to have fled their homes,” said UN humanitarian agency OCHA said in an update Tuesday, warning that “this number is expected to rise further”. It said that around 3,000 people had been displaced “due to previous escalations”. The Israeli bombing campaign has destroyed more than 1,000 housing units, and 560 have been so severely damaged they are uninhabitable, OCHA said, citing Palestinian authorities. Among the displaced, nearly 175,500 people sought shelter in 88 schools run by the UN agency supporting Palestinian refugees, UNRWA, it said. More than 14,500 others had fled to 12 government schools, while close to 74,000 were estimated to be staying with relatives and neighbours or seeking shelters in churches and other facilities. The number of displaced people inside of Gaza “represents the highest number of people displaced since the 50-day escalation of hostilities in 2014,” it said. “Meeting basic needs is becoming increasingly challenging for those who have not been displaced,” OCHA warned. Palestinian media said Israeli airstrikes hit homes in Gaza City, the southern city of Khan Younis and in the Bureij refugee camp in central Gaza. One home struck belonged to the father of Mohammed Deif, the leader of Hamas’ armed wing in Gaza, reports said. Deif’s brother and other family members were killed, according to the reports. Residents appealing for help on social media said many buildings had collapsed, sometimes trapping as many as 50 people inside with rescue workers unable to reach them. At the morgue in Gaza’s Khan Younis hospital, bodies lay on the ground on stretchers with names written on their bellies. Medics called for relatives to pick up bodies quickly because there was no more space for the dead. A municipal building was hit while being used as an emergency shelter. Survivors there spoke of many dead. “No place is safe in Gaza, as you see they hit everywhere,” said Ala Abu Tair, 35, who had sought shelter there with his family after fleeing Abassan Al-Kabira near the border. Two members of Hamas’ political office, Jawad Abu Shammala and Zakaria Abu Maamar, were killed in an air strike in Khan Younis, a Hamas official said. The Palestinian Foreign Ministry said Israeli strikes had since Saturday destroyed more than 22,600 residential units and 10 health facilities and damaged 48 schools. “Such blatant dehumanization and attempts to bomb a people into submission, to use starvation as a method of warfare, and to eradicate their national existence are nothing less than genocidal,” Palestinian UN envoy Riyad Mansour wrote in a letter to the UN Security Council on Tuesday, seen by Reuters. Violence also flared in the occupied West Bank and in East Jerusalem, where Israeli police claimed they killed two Palestinians who shot fireworks toward officers on Tuesday night. In the West Bank, 21 Palestinians have been killed and 130 injured in clashes with Israeli forces since Saturday, according to the Palestinian health ministry. At the White House, Biden called the Hamas attacks “an act of sheer evil” and said Washington was rushing additional military assistance to Israel, including ammunition and interceptors to replenish the Iron Dome aerial defense system. He called for Israel to follow the “law of war” in its response. He told reporters the United States had “enhanced our military force posture in the region to strengthen our deterrence,” including by moving an aircraft carrier strike group and fighter aircraft. “Let me say again to any country, any organization, anyone thinking of taking advantage of the situation, I have one word: don’t,” said Biden, in an apparent reference to Iran and its proxies in the region. US officials say they do not have evidence Iran orchestrated the attacks, but point to Iran’s long-term support for Hamas. Former Hamas chief Khaled Meshaal called for protests across the Arab world on Friday in support of the Palestinians, in a recorded statement seen by Reuters. “[We must] head to the squares and streets of the Arab and Islamic world on Friday, the Friday of Al Aqsa Flood,” said Meshaal, who is currently the leader of Hamas’s diaspora office. Biden despatched his top diplomat Antony Blinken to Israel, who will deliver “a message of solidarity and support,” State Department spokesperson Matthew Miller said. US national security adviser Jake Sullivan said Washington was talking also with Israel and Egypt about the idea of creating a safe passage for civilians out of Gaza.