About 20 trucks carrying food, water and medical supplies may be allowed to enter Gaza in the coming days.
Israel cut electricity, most water and stopped deliveries of food and medicine to Gaza following an attack by Hamas militants on 7 October.
Since then, Gaza’s 2.1 million residents have been rapidly running out of basic supplies.
But leading humanitarian organisations warn the aid delivery will only be a drop in the ocean.
“The UN has reported that a minimum of 100 trucks of humanitarian assistance are needed in order to support the 2.3 million civilians living in Gaza.”, Shaina Low of the Norwegian Refugee Council told the BBC.
Currently, only 20 are believed to be due to allowed in.
Even before the war started, 1.2 million people relied on food aid from UNWRA, Juliette Touma, the UN body’s spokeswoman in Amman, told the BBC.
“Poverty is very, very high in the Gaza Strip. Already before the war the situation was desperate. Now it is becoming tragic,” she said.
The agreement to deliver a limited amount of aid via Egypt’s Rafah crossing was reached by US President Joe Biden and Egypt’s president, Abdul Fattah al-Sisi, on Wednesday.
Mr Biden called Mr al-Sisi following a brief visit to Israel.
Israeli Prime Minister Benjamin Netanyahu confirmed on Wednesday that Israel would not prevent supplies going from Egypt to the civilian population in southern Gaza.
However, the government only agreed to allow food, water and medical supplies – not other much-needed supplies like fuel.
A UN report on Gaza said that fuel is a necessity, and a lack of fuel is contributing to the water crisis, as desalination plants and water pumps could no longer operate.
More on Israel-Gaza war
The aid agreement offers a glimmer of hope for millions inside Gaza. Prior to these negotiations, it had been unclear how any aid would reach civilians.
Israel said it would not allow any aid to pass through its own territory until hostages being held by Hamas were released, and aid has been unable to cross the Rafah crossing through Egypt.
Speaking to the BBC’s Newshour, Egypt’s Foreign Minister Sameh Shoukry said that was because the crossing had been subject to four aerial bombardments, and that there had been no authorisation for the safe passage of lorries and trucks into Gaza.
“I would hope there would be a determination as to why the crossing is being bombarded and by whom it’s being bombarded”, he said.
The exact timeline on when aid will get to those who need it remains unclear. The road on the Rafah crossing requires repairs before any trucks are able enter.
But Mohsen Sarhan from the Egyptian Food Bank said time – as well as supplies – is running out. He said 120 lorries were ready to deliver aid and were waiting at the border for safe passage.
“We’re very angry because we know people over there have run out of water. They have even run out of body bags. They have run out of everything.”