Israeli airstrikes hit two schools and a hospital complex in Gaza on Sunday, killing at least 30 people, amid reports of heated disagreements between US and Israeli leaders about a possible ceasefire deal.

Inside Israel, a Palestinian stabbed two people to death in a city near Tel Aviv, adding to tensions as the country braces for Iran’s response to the assassinations of key allies this week.

Fears of an all-out war in the region escalated after Hamas’s political leader Ismail Haniyeh was killed in Tehran and an Israeli airstrike hit Hezbollah’s second-in-command in Beirut. Iran has sworn revenge.

An Israeli military spokesperson warned the country’s air defence systems were “not airtight” and urged the public to be alert, as the prime minister, Benjamin Netanyahu, said the country was already in a multi-front war with Iran and its allies.

France and Italy became the latest countries to urge their citizens to leave Lebanon, as Israelis reported GPS jamming around Tel Aviv on Sunday, something the military has said in the past it does to counter the threats of drones and missiles.

The US has promised to defend Israel, ordering an aircraft carrier to sail to the region and moving other military assets into position.

Despite that solidarity in the face of a potential Iranian attack, the US president, Joe Biden, has been open about concerns that the killing of Haniyeh will complicate efforts to stop the fighting in Gaza, which is key to regional de-escalation.

He had a “heated conversation” this week with Netanyahu, who was forced to deny that he was an obstacle to a ceasefire and hostage release deal, the New York Times has reported, quoting a senior US official.

That was just the latest confrontation between two increasingly uneasy allies. Biden reportedly told the Israeli leader to “stop bullshitting me” when they discussed the return of hostages at an in-person meeting at the White House late last month.

“Biden realised that Netanyahu was lying to him about the hostages,” the Haaretz newspaper quoted a senior administration official as saying.

Biden’s reported scepticism about Netanyahu’s commitment to the return of Israeli hostages puts him on the same page as Israel’s defence chiefs. They believe the country’s leader is not interested a ceasefire deal even though they consider a workable proposal to be on the table, Israeli media reported this week.

Israeli airstrikes on two schools in Gaza City killed at least 25 people sheltering there on Sunday, and another attack on the courtyard of al-Aqsa hospital killed at least five people and set the tents of displaced people on fire.

The hospital is the main medical facility in the central city of Deir al-Balah, but its grounds have become an informal settlement for people who have fled their homes, many of them displaced various times as Israeli troops have moved across the strip during 10 months of war.

Video from the Associated Press showed men trying to put out fierce flames in the early morning dark and rescue the injured. A second strike on a nearby home killed a girl and her parents, the hospital said.

Those attacks came the day after 16 people were killed and 21 injured in a previous airstrike on displaced people sheltering in another school in Gaza City. The UN says 85% of school buildings in the Gaza Strip have been directly hit or damaged.

Israel’s military said it had struck Hamas command centres at the schools, and that the hospital strike targeted a militant, without providing further details or evidence.

The majority of the 2.3 million population have been displaced from their homes, many various times.

Many have been living for months in makeshift tent encampments or overcrowded shelters in shrinking “humanitarian zones”, which Israel still sometimes hits with airstrikes. The Israeli military also issued new evacuation orders on Sunday for parts of Khan Younis in southern Gaza.

The toll from the war in Gaza reached 39,580 on Sunday, the territory’s health authorities said. Not all the dead have been identified, but civilians make up a majority of the 25,000 who have been named.

Thousands more are buried under the rubble or at risk from hunger and infectious diseases, whose spread is fuelled by the lack of clean water and sanitation across Gaza.

There has been a “frightening increase” in cases of hepatitis A to 40,000 since the war started from 85 in the same period a year ago, the head of the UN’s Palestinian relief agency (Unwra), Philippe Lazarrini said on Friday.

Polio has also been detected in waste water, putting many children there who are unvaccinated or have not completed the course of vaccination at risk of infection and possible paralysis.

The Israeli military announced in late July that it would offer a booster course of polio vaccine to troops serving in Gaza.

The WHO has said it is sending 1m polio vaccines, but warned it is not enough just to get them over the border, calling for a ceasefire to ensure all children who need coverage can be reached.

Israel launched its campaign in Gaza after cross-border Hamas attacks on 7 October, during which 1,200 people, most of them civilians, were killed and about 250 taken hostage.

The stabbings in Israel on Sunday took place in Holon, just south of Tel Aviv, in a park and near a fuel station. The victims were a woman in her 70s and a man in his 80s. Two men were injured, Israel’s ambulance service said.