Damaged aid trucks are pictured after an airstrike on the rebel held Urm al-Kubra town, western Aleppo city, Syria, Sept. 20, 2016. 

The Syrian Red Crescent sent out a tweet saying they were sending 31 trucks full of aid into opposition territory in the Aleppo countryside. Shortly afterwards, missiles hit an aid convoy -- more than 20 trucks full of food, medicine and other essential supplies -- and the Syrian Arab Red Crescent (SARC) warehouse where they were unloading the humanitarian relief. The international Red Cross said that some 20 civilians were killed in the strike. The U.N. said it was suspending all humanitarian aid convoys in Syria in the wake of the airstrike.

A few days before a U.S. airstrike hit Syrian soldiers by mistake said the Pentagon. The strikes contributed to an unraveling of the cease-fire agreement. 

A still image taken on August 18, 2016 from a video posted on social media by the Aleppo Media Center said to be shot in Aleppo on August 17, 2016, shows 5-year-old Omran Daqneesh with bloodied face sitting in an ambulance, after an airstrike, in Syria. Daqneesh was rescued along with three siblings, ages 1, 6 and 11, and his mother and father. His brother, Ali, later died. 

The image of the stunned and weary-looking boy, sitting in an ambulance caked with dust and with blood on his face, captured the horror that has beset the contested northern city with the photograph of the child widely shared on social media.

A still image taken on September 27, 2016 from a drone footage obtained by Reuters shows damaged buildings in a rebel-held area of Aleppo, Syria. 

Despite attempts at a cease-fire, Aleppo suffered its heaviest airstrikes on rebel-held areas of the northern city in five years. 

A fragile Syrian cease-fire, that began February 27, 2016, fell apart as the northern city of Aleppo was battered by a week of air strikes, rocket fire, and shelling. A series of airstrikes hit a hospital and nearby buildings in the rebel-held part of Syria’s contested city of Aleppo overnight on April 27-28, 2016, killing at least 20 people -- including three children and the last pediatrician in the city. A Syrian monitoring group said more than 120 people have been killed in rebel-controlled Aleppo over the last week, including 18 children.

Here, a Syrian boy is comforted as he cries next to the body of a relative who died in a reported airstrike on April 27, 2016 in the rebel-held neighborhood of al-Soukour in the northern city of Aleppo.

Syrians help a wounded youth following an air strike on the Fardous rebel held neighborhood of the northern Syrian city of Aleppo on April 26, 2016.

The strikes on the hospital, specializing in pediatric care, hit shortly before midnight April 27, according to opposition activists and rescue workers. They struck a well-known field hospital in the rebel-held district of al-Sukkari in Aleppo.

The dead included the last pediatrician remaining in the city’s opposition-held areas and a dentist, activists and a British surgeon who knows the hospital told CBS News.

An injured woman reacts at a site hit by airstrikes in the rebel-held area of Old Aleppo, April 28, 2016.

Violence intensified, with the government claiming rebel shells had killed at least 30 people as they left a mosque. Opposition groups, meanwhile, reported fresh airstrikes Friday, April 29, on rebel-held areas in the southern parts of the sprawling city.

While it remains unclear exactly who is behind those airstrikes, the Syrian regime, with its backers in Russia and Iran, has been trying to recapture all of Aleppo from rebel forces.

A boy injured in a strike that destroyed the al-Quds hospital in southern Aleppo, Syria, receives treatment at another facility in the front-line city, in a screen grab from video posted online by Syrian opposition activist group Buraq Media Foundation, April 28, 2016.

Doctors Without Borders, which is also known by the acronym MSF, said two doctors were among 14 people killed in the strike on the hospital.

In an online statement April 28, Doctors Without Borders (MSF) said it had been donating medical supplies to Al-Quds since 2012. The organization condemned the “outrageous” air strike on a hospital it was supporting in the war-torn northern Syrian city.

A picture taken on April 28, 2016 shows a general view of the damaged Al-Quds hospital building (R) following airstrikes on the rebel-held neighborhood of Sukkari in the northern city of Aleppo.

The French news agency AFP reported, citing an anonymous Syrian official, the army was preparing to launch a massive offensive to retake the entire city of Aleppo in the coming days.

A man follows rescuers carrying the body of a boy on a stretcher following an air strike on the rebel-held neighborhood of al-Kalasa in the northern Syrian city of Aleppo, on April 28, 2016.

A Syrian family runs for cover amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighborhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016.

Fresh bombardment shook Syria’s second city Aleppo, severely damaging a local clinic as outrage grows over an earlier air strike that destroyed a hospital.

Syrian men carry a body on a stretcher amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighborhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016.

The death toll from an upsurge of fighting in Syria’s second city Aleppo rose despite a plea by the UN envoy for the warring sides to respect a February ceasefire.

Syrian men carry an injured youth in the government-controlled side of the northern city of Aleppo, following fighting between regime forces and rebels on April 28, 2016.

The Syrian army was preparing an offensive to retake the whole of Aleppo, as fighting in the divided city renewed.

UN envoy Staffan de Mistura pleaded for urgent action by cosponsors of the cease-fire, Russia and the United States, to rescue it. But pro-government newspaper Al-Watan said the army was now poised for a “decisive battle” for Aleppo and the surrounding province which would begin in the coming days.

Syrians inspect the damage in the government-controlled side of the northern city of Aleppo following fighting between regime forces and rebels on April 28, 2016.

Once home to some 2.5 million residents and considered Syria’s economic powerhouse, Aleppo has been divided between government and opposition control since shortly after fighting there began in mid-2012.

A Syrian civil defense member carries a wounded woman into a hospital in the government-controlled side of the northern city of Aleppo following fighting between regime forces and rebels on April 28, 2016.

Some 2,000 civilians, including more than 500 children, have been killed in regime air strikes on rebel-held areas of Aleppo since January 2014, many of them in barrel bomb attacks.

A man gestures amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighborhood of al-Kalasa in the northern Syrian city of Aleppo, on April 28, 2016.

The death toll from an upsurge of fighting in Syria’s second city Aleppo rose despite a plea by the UN envoy for the warring sides to respect a February ceasefire.

Syrians evacuate a toddler from a destroyed building following a reported air strike on the rebel-held neighborhood of al-Kalasa in the northern Syrian city of Aleppo, on April 28, 2016.

Syrian civil defense volunteers evacuate a woman from a destroyed building following a reported air strike on the rebel-held neighborhood of al-Kalasa in the northern city of Aleppo, on April 28, 2016.

Syrians evacuate an injured man amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighborhood of Al-Qatarji, in the northern Syrian city of Aleppo, on April 29, 2016.

Syrian civil defense volunteers and rescuers remove a baby from under the rubble of a destroyed building following a reported air strike on the rebel-held neighborhood of al-Kalasa in the northern Syrian city of Aleppo, on April 28, 2016.

The siege of Aleppo caused a humanitarian catastrophe. The Syrian government escalated the situation in 2012 with the use of barrel bombs, frequently hitting civilian targets. Russian airstrikes beginning in late 2015 intensified an already horrific situation. The vast majority of victims have been civilians.

According to the UN some 300,000 people still live in the once thriving city.