Six United Nations workers and several others were killed in an Israeli air strike on a school compound sheltering hundreds of displaced Palestinians in central Gaza.
Few details are currently publicly available, but the heads of the UNRWA relief agency have given some information.
Here's what we know.
What happened?
On Wednesday afternoon local time, two Israeli strikes hit a school in the Nuseirat camp in central Gaza, UNRWA said.
The Al-Jaouni school is one of dozens that the agency runs and has been used as a shelter since the breakout of the war.
"It is home to around 12,000 displaced people, mainly women and children," the agency said.
This was the fifth time the school was hit and yielded the largest death toll of UNRWA staff from a single incident in the agency's history.
The UN had earlier said the site was previously deconflicted with the Israeli forces.
Displaced Gazan Hani Haniyeh described the chaos that unfolded.
"Body parts. The sound of an explosion shook the building. We went out running and saw body parts thrown everywhere in the shelter," he said.
"Unfortunately, my children are still missing. Four of my children. I do not know where they are. I do not know where my daughters are.
"Even my wife is sleeping here in this corner. Where is my wife? I do not know. I don't know where my wife is."
Who was killed?
So far, the death toll is reportedly as high as 18 people.
"Among those killed was the manager of the UNRWA shelter and other team members providing assistance to displaced people," the agency said.
The Gaza Government Press office reports the total to be 18, while officials from Awda and al-Aqsa Martyrs hospitals said at least 14 people were killed.
Arabic media Palestine Today spoke to a father who said his young son Obaida was killed in the strike, and showed footage of his body being carried through the street.
People were seen collecting body parts in plastic bags. Local media reported at least 22 people were also injured.
At least 220 UNRWA staff have been killed so far in the conflict, according to the UN.
The agency's Washington director Bill Deere said this made the Gaza war the deadliest conflict in terms of staff loss in UN history.
"There have been to date 464 incidents logged of damaging 190 UNRWA installations, some of them several times over," he told ABC News Channel.
"As a result, almost 600 displaced civilians who were sheltering at UN schools or facilities under the blue flag have been killed, with another 1,800 injured."
More than 41,000 people have been killed in Gaza since October 7.
What was the school?
The al-Jaouni school was a preparatory boys school run by the relief agency, which runs the largest school system in the enclave.
It was turned into an emergency shelter after the war started.
It is located in the Nuseirat camp in central Gaza, a part of which is included in the shrinking humanitarian area.
"This is where people literally shelter under the protection — well, the sort of protection, I suppose these days — of the UN blue flag," Mr Deere said.
"We provide food as such as we can, medicine, social services, like psychosocial support for the children."
Why did Israel hit the school?
Just after the air strike, the Israel Defense Forces (IDF) published a statement confirming it had hit the school.
It claimed the strike was on "on terrorists who were operating inside a Hamas command and control center in the area of Nuseirat in central Gaza … which was embedded inside a compound that previously served as the Al Jaouni School."
It added that it took "numerous steps" prior to the strike "to mitigate the risk of harming civilians, including the use of precise munitions, aerial surveillance and additional intelligence."
Mr Deere said the IDF knows the GPS locations of every UNRWA facility, which are updated daily, and all movements are coordinated with them.
"UNRWA [does] not wake up in the morning and say, 'Today I'll drive to X and deliver water.' It all has to be coordinated in advance."
What has the reaction been?
The UN condemned the attack immediately.
UNRWA Commissioner-General Philippe Lazzarini blasted the "endless and senseless killing, day after day."
"Humanitarian staff, premises & operations have been blatantly and unabatedly disregarded since the beginning of the war," he wrote on X.
"The longer impunity prevails, the more international humanitarian law and the Geneva Conventions will become irrelevant."
Mr Deere said international humanitarian law was clear in that civilian casualties must be minimised.
"Raining down air strikes on a shelter with thousands of people at it, I think, is very hard to justify the results over the intention."
In its post on X, UNRWA simply said "Just Tragic. No one is safe in Gaza. No one is spared."
It added a call to protect civilian infrastructure. "They are not a target."
What is UNRWA?
UNRWA is short for the United Nations Relief and Works Agency for Palestine refugees in the near east.
Founded in 1949, it is one of the UN's oldest and largest organisations and the only aid agency dedicated to a specific group of people.
It is funded primarily by international donors, including Australia. Many countries stopped their donations following accusations of staff members taking part in the October 7 attacks before later restarting them except for the United States.
Before October 7, it had more than 13,000 staff working in more than 300 installations in the Gaza strip. It has thousands more in several other countries who have Palestinian refugee populations.
It delivers humanitarian aid, food, education, health and numerous other services to registered refugees and is part of the aid effort vaccinating children from polio in the strip.
Not an isolated incident
Nearly 300 humanitarian aid workers, of whom two-thirds were UN staff, have been killed in the Gaza war, according the UN.
UN Secretary-General Antonio Guterres said the lack of accountability for the killings was "totally unacceptable" and called for investigations.
"We have courts, but we see that the decisions of courts are not respected, and it is this kind of limbo of accountability that is totally unacceptable and that requires also a serious reflection," Mr Guterres told Reuters.
In April, a convoy from charity organisation World Central Kitchen was targeted, killing Australian aid worker Zomi Franckom.
The IDF later said it was a grave mistake and dismissed two officers from their positions and reprimanded three others.
On Monday, the Israeli military detained for eight hours a convoy of UN staff heading to northern Gaza as part of the polio vaccination campaign.
"The Israeli army stopped a UN convoy … despite prior detailed coordination," the UNRWA commissioner-general Philippe Lazarrini said at the time.
"The convoy was stopped at gun point just after the Wadi Gaza checkpoint with threats to detain UN staff.
"Heavy damage was caused by bulldozers to the UN armoured vehicles."
What comes next?
Mr Deere said what happened was "not a unique experience although it's a very hard one for us today because of the loss of so much staff at one time."
"The longer the world kind of turns a blind eye to the violations of international humanitarian law and the Geneva Conventions, frankly the more they become irrelevant," he said.
"I think there's actors in the world who are standing by watching and noting this indifference and, you know, it starts in Gaza, but it might not end there."
But he said this will not deter the more than 33,000 staff the organisation boasts across its operations, most of who are Palestinian refugees themselves.
"I have never been prouder to work with a group of people like this," he said.
"Many of them have been displaced multiple times, but they just make you proud to work for the United Nations.
"They'll be up again tomorrow, they'll be back, and they'll be doing their job."
