Alone in an ambulance, the boy - identified by doctors as five-year-old Omran Daqneesh - tries to wipe the blood off his head, unaware of the injury he has sustained.
Video of children being pulled from the rubble of a building hit by air strikes in Aleppo has been widely circulated on social media, causing upset and condemnation over the harrowing reality of Syria's five-year war.
Aleppo, split into rebel- and government-controlled areas, has become the focus of fighting in Syria's five-year conflict.
Rebel-held areas are suffering heavy air strikes daily as pro-government forces try to retake territory lost to rebels two weeks ago in the southwest of Aleppo.
The video was shot on Wednesday in the rebel-held al-Qaterji neighbourhood of the city.
It shows an aid worker carrying the little boy out of a building and placing him on a seat inside an ambulance, before rushing back out to the bombed-out scene. The boy sits alone, stunned, before two more children are brought into the vehicle. A man with blood on his face then joins them.
Last year, international sympathy for victims of Syria's war was heightened by a photo of a drowned 3-year-old refugee from Syria, Alan Kurdi, washed up on a Turkish tourist beach. The image of Aylan, who died when a people smugglers' boat taking his family and other refugees to a nearby Greek island capsized, swept across social media and was retweeted thousands of times.