The largest hospital in Gaza, where up to 50,000 people are sheltering, is facing bombardment, the World Health Organization has said, as the US’s top diplomat said “far too many Palestinians have been killed” in the war. Palestinian officials said Israel launched airstrikes on or near four hospitals and a school on Friday, killing at least 22 people. The bombardment came as the territory’s precarious health system struggled to cope with thousands of people wounded or displaced in Israel’s war against Hamas militants. Graphic daytime videos posted online appeared to show screaming and bloodied people, including children, in the grounds of al-Shifa hospital in the heart of Gaza City. The Reuters news agency said it had verified the footage and that one person had died. Another video, filmed at night-time, reportedly showed the aftermath of an earlier attack. The US secretary of state, Antony Blinken, said on Friday that he welcomed Israel’s agreed four-hour humanitarian pauses in its Gaza offensive, but that more needed to be done. “Far too many Palestinians have been killed. Far too many who suffered these past weeks, and we want to do everything possible to prevent harm to them and to maximise the assistance that gets to them,” he said. Margaret Harris, a WHO spokesperson, said 20 hospitals in Gaza were out of action and that there was “intense violence” at Shifa. “I haven’t got the detail on al-Shifa but we do know they are coming under bombardment,” she said. Harris said there was also “significant bombardment” on Rantisi hospital, the only hospital providing paediatric services in north Gaza. She said children had been receiving care such as dialysis and life support – “things that you cannot possibly evacuate them safely with”. The hospital was surrounded by Israeli armoured vehicles on Friday, according to the Agence France-Presse news agency. At the same briefing, the UN humanitarian office spokesperson Jens Laerke said: “If there is hell on earth today, its name is northern Gaza. It is a life of fear by day and darkness at night and what do you tell your children in such a situation, it’s almost unimaginable – that the fire they see in the sky is out to kill them?” The Palestinian Red Cross said Israeli snipers shot at al-Quds hospital, to the south of Gaza City, and that there were violent clashes, with one person killed and 28 wounded, most of them children. “Israel is now launching a war on Gaza City hospitals,” said Mohammad Abu Selmeyah, the director of Shifa. The Red Cross said medical facilities and workers in Gaza needed to be protected, warning the health system in the territory had “reached a point of no return”. “The destruction affecting hospitals in Gaza is becoming unbearable and needs to stop,” William Schomburg, head of the ICRC sub-delegation in Gaza, added on Friday. An Israel Defence Forces (IDF) spokesperson said: “Earlier today, the IDF received reports of a hit on the Shifa hospital in Gaza City. The Hamas-run media office in the Gaza Strip immediately claimed that this was a strike carried out by the IDF. An examination of IDF operational systems indicates that a misfired projectile launched by terrorist organisations inside the Gaza Strip hit the Shifa hospital. The misfired projectile was aimed at IDF troops operating in the vicinity.” In an earlier media briefing, IDF spokesperson Lt Col Richard Hecht said: “The IDF does not fire on hospitals. If we see Hamas terrorists firing from the hospitals, we’ll do what we need to do. “We’ll take every [pre]caution possible to make sure we don’t come and raid people on drips or with broken bones.” Israel’s military has long accused Hamas of using civilian institutions as cover for military bases. In a statement on Thursday, the Israeli army said infantry and special forces backed up with air support had raided the military quarters of Hamas near Shifa. The IDF said Shifa was situated in an area they called “the heart of intelligence and operational activities” for Hamas when it planned the 7 October attacks. Hamas and hospital staff have denied this, saying the IDF is using the allegation as a pretext to strike the hospital. Early on Friday, strikes hit the courtyard and the obstetrics department of Shifa, according to Ashraf al-Qidra, the Gaza ministry of health spokesperson. Palestinian media published video footage of Shifa that they said showed the aftermath of an Israeli attack on a car park where displaced Palestinians were sheltered and journalists were observing. “With ongoing strikes and fighting nearby [Shifa], we are gravely concerned about the wellbeing of thousands of civilians there, many children among them, seeking medical care and shelter,” Human Rights Watch said online. Qidra added on Friday: “Israeli military tanks are now surrounding hospitals in Gaza including al-Rantisi, Nasser hospital for children, eyes and mental health services. “Thousands of patients, medical staff and displaced persons are inside the hospitals without access to water, and food and can be targeted any moment.” At least 20 people were killed in strikes that hit Gaza City’s al-Buraq school, said Abu Selmeyah, the director of Shifa where the dead were taken. The strikes have triggered a mass exodus of the displaced. Thousands of Palestinians continued to flee south from northern Gaza on Friday, including some of those sheltering at Shifa and Rantisi. The White House announced on Thursday that Israel would begin to implement four-hour “humanitarian pauses” in parts of the area to allow people to leave. The US national security spokesperson, John Kirby, said the pauses would allow people to pass along two humanitarian corridors, which he described as “a significant first step”. But in the hours after the statement there was no sign of a letup in the fighting that has laid waste the coastal territory. Israel’s bombardment of Gaza has killed more than 11,000 Palestinians since Hamas militants rampaged through southern Israeli communities on 7 October. Officials initially said about 1,400 people, mostly civilians, were killed in those attacks, but on Friday that figure was revised down to about 1,200. “This is the updated number,” ministry spokesperson Lior Haiat told AFP. “It is due to the fact that there were lot of corpses that were not identified and now we think those belong to terrorists … not Israeli casualties.”