Warning: This video contains footage that may disturb some viewers.
UNICEF says there are 100,000 children under siege in the Syrian city of Aleppo.
The images of young Omran Daqneesh shocked the world last week, as he was pulled from the rubble earlier this week. His house, in a rebel-held part of the city, was hit by bombs dropped by Syrian and Russian jets.
His brother Ali was also caught in the attack, and has since died.
UNICEF wants urgent action.
"What human being can see the stunned suffering of Omran Dagneesh, the small boy rescued from a destroyed building in Aleppo, Syria, and not feel an overwhelming sense of empathy?" executive director Anthony Lake said in a statement.
"Can we not extend the same empathy to the more than 100,000 children also trapped in the horror that is Aleppo? They are all suffering things no child should suffer - or even see."
Watch the video for the full Channel 4 report.