(CNN) Madaya seemed healthier at first to Hannah Singer, as if the delivery of first aid four days earlier had brought some life back onto the streets.
But then the UNICEF Syria chief went into the basement of the makeshift hospital, where she saw two skeletal figures bunched together on one mattress before her.
One of her colleagues rushed forward to check their pulses.
Both were teenage boys, one of them barely stirring, weak beyond speech. His name was Ali, and he was fading.
"One of them did not have a pulse, and the other was very low. Ali passed away before my eyes," Singer said. "It was almost surreal.
"The boy next to him whispered, 'Did he die, did he die?' The doctor who tried to resuscitate Ali told him, no, it was OK, and he should take care of himself. We asked his family to move him out of the room. They were almost too tired and exhausted to mourn. It was all over in five minutes," Singer said.
UNICEF hopes that the other boy can be moved out of the town shortly, yet fear for his health.
In a war where food has long been a weapon of war, the fate of Madaya has shone a brief spotlight on a savage tactic of war that aid workers say all sides are guilty of exploiting.
"We need to remind the world that Madaya is one of 15 places that are besieged," Singer said. "We do not need finger pointing. All parties are engaged in this. We need the lifting of all sieges."
Starvation in Syria a 'war crime'
The United Nations says 400,000 Syrians badly need food aid.
It will be little comfort to them that it took Madaya sinking to staggering depths of starvation -- publicized by an intense social media campaign -- for help to finally arrive.
But the week has shown that negotiation and quid pro quos can get food and aid through to the most vulnerable, and, most rarely in this brutal conflict, that all sides now see a role for dialogue to alleviate the worst excesses in the battlefield.
The second delivery of aid into Madaya caps an extraordinary week of suffering and its alleviation for the town, whose fate has been linked to two similarly besieged towns in northern Syria that -- unlike Madaya -- are loyal to the Syrian government: Fua and Kefraya.
The siege of the three towns remains intensely politicized and subject to claim and counter-claim. Syrian opposition activists have accused the United Nations of "assisting" the siege by requiring government permission to take aid into the towns.
Hezbollah, the Lebanese militant and political group that is accused by opposition activists of helping the Syrian government's siege of Madaya, released a statement late Friday in which it denounced some media coverage of the siege.
They said several images of starving Madaya residents that were used to portray the siege were fabricated.
And indeed, some of the images posted online by activists later turned out to be from other hunger-stricken towns in the conflict's long past.
The Hezbollah statement blamed "the long delay of the humanitarian aid entry" on "the militants' refusal of letting aid into the towns of [Fua and Kefraya] simultaneously."
How did things get so bad in the starving Syrian town?
Monday's first delivery faced various hurdles at the series of government checkpoints into Madaya, often linked with the need to simultaneously match the progress of the convoy into Fua and Kefraya.
But once inside, experienced aid workers were moved to tears. They were shocked by the politeness of emaciated children, able only to plead plaintively for "french fries and ketchup" or for a biscuit.
And they were humbled that families who had been reduced to eating "siege soup" -- just hot water with spices -- offered the aid workers the hospitality of what little food they had.
The situation inside of Madaya remains bleak for many of the residents, yet a U.N. source who traveled with the first and second aid convoys described how, on Thursday, "There were some smiles on some faces after their first meal in days."
Families who had earlier offered them siege soup were able to provide hospitality to the aid workers, offering the very food the convoy had brought them.
Thursday was also the first time the aid workers were able to "bring in doctors and nutritionists," the U.N. source said.
The medics went door to door to make inquiries.
"They all came up with the same conclusion -- that there are large numbers of malnourished, and it is not just children but adults too. That is uncommon. There were children who could not answer our questions or make the smallest movement," the U.N. source said.
The source added that next to the 16-year-old boy whose death the UNICEF team witnessed was a man in his 20s who was in dire need of evacuation for hospital treatment.
They were not able to evacuate him, but hope to take out a pregnant woman and two others in exchange for three patients being evacuated from Fua and Kefraya.
A misunderstanding outside one of the towns almost jeopardized the delivery of urgently needed wheat flour, and highlighted how mistrust has permeated and hampered the negotiations and deliveries.
Outside Fua, one truck was stuck in the mud, causing the chain that bound its back doors to break, said the U.N. source. This led to about 50 bags of flour falling out or being damaged. Militants from the rebel group Jaish al Fateh, when they later saw the bags, suspected the damage was somehow deliberate, and it took hours to reassure all sides an accident had happened.
Eventually the trucks were all allowed in, with the understanding that those damaged and missing outside of Fua would be replaced in the next delivery, which aid workers hope will be on Sunday or Monday.
The U.N. source also recounted how they had received a message Friday morning from an 11-year-old boy, Mohammed, whom they had seen standing by the aid convoy until 2 a.m. He said simply how this morning they had used wheat flour to bake, and for the first time in eight months, he had eaten bread.