A young boy walks past a makeshift barricade made of wreckage of buses to obstruct the view of regime snipers and to keep people safe in the rebel-held side of the northern Syrian city of Aleppo on March 14, 2015.

A man evacuates a child from a building following a reported barrel bomb attack by Syrian government forces on the northern Syrian city of Aleppo, on May 30, 2015. AFP PHOTO / KARAM AL-MASRI

Syrian rescue workers and citizens carry a child on a stretcher from a building following a reported barrel bomb attack by Syrian government forces at the Al-Firdaws neighbourhood of the northern Syrian city of Aleppo, on May 30, 2015. . AFP PHOTO / KARAM AL-MASRI　

People gather at the scene after Syrian government forces allegedly dropped barrel bombs on the northern Syrian city of Aleppo, on May 30, 2015. AFP PHOTO / KARAM AL-MASRI

A Syrian man carries his two girls as he walks across the rubble following a barrel bomb attack on the rebel-held neighbourhood of al-Kalasa in the northern Syrian city of Aleppo on September 17, 2015. AFP PHOTO / KARAM AL-MASRI

Syrian rescue workers and citizens evacuate people from a building following a reported barrel bomb attack by Syrian government forces on the central al-Fardous rebel held neighbourhood of the northern Syrian city of Aleppo, on June 9, 2015. AFP PHOTO / KARAM AL-MASR

A Syrian rescue worker carries the body of a child removed from under the rubble of destroyed buildings following reported airstrikes by government forces on the rebel-controlled part of Aleppo’s Maadi residential district, on June 21, 2015. AFP PHOTO / KARAM AL-MASRI

CORRECTING LOCATION A Syrian man sits in the rubble following a barrel bomb attack the previous day on the rebel-held neighbourhood of al-Mashad in the northern Syrian city of Aleppo on September 17, 2015. AFP PHOTO / KARAM AL-MASRI

Civilians photographed in a damaged building in Syria’s northern city of Aleppo following a reported air strike by government forces on December 7, 2015. KARAM AL-MASRI / AFP PHOTO