The World Health Organisation said many of those still trapped in the city are injured women and children who need medical attention
Thousands of civilians remain trapped in eastern Aleppo - in spite of reports that a deal has been reached to allow the evacuation to resume.
Russia has said 9,500 people - including rebel fighters and their families - have now left the besieged Syrian city.
The World Health Organisation said many of those still trapped in the city are injured women and children who need medical attention.
Sonia Khush from the charity, Save the Children, said people who have escaped Aleppo are in a state of trauma:
“Our teams describe them as arriving in a complete state of shock from everything they have gone through,” she said.
“They are weak. Children are malnourished. They are showing a lot of signs of distress and trauma from having lived under siege for the last five months.”
A White Helmet rescue worker in the city has told Sky News that people were shot by pro-government forces as they tried to flee the "hell" of Aleppo.
Ishmael al Abdullah, of the Syria Civil Defence group, described the "dangerous journey" faced in trying to escape the eastern rebel enclave and said tens of thousands remained trapped and were desperate to leave.
The International Committee of the Red Cross (ICRC) has called on the warring factions to agree a plan to provide a safe passage for evacuees.
Both sides now claim to have reached a deal to allow the evacuation to resume, although this will inevitably be fragile.
Russia has been accused of failing to "restrain" Iranian-backed militias to allow for the evacuation to continue.
Speaking to Sky News, Mr Abdullah said more than 40,000 people remain trapped.
"Yesterday they opened fire on the people who were trying to escape from this hell - they killed three people,” he said.
"Assad mercenaries killed the three people in cold blood in front of the Red Crescent and all the guys who witnessed that crime… Now we are waiting for the new deal.”
"Up to now we do not trust anyone. Up till now we haven't seen any deal and no one saw up to now the green buses [used to take civilians out of Aleppo]."
Meanwhile, a convoy carrying enough supplies to build a children's hospital near Aleppo is due to leave central London for Syria.
Around 3,000 people have donated nearly £150,000 to fund what organisers say is the first ever crowd-funded hospital.