Tributes for Syrian paediatrician Muhammad Waseem Moaz
Dr Muhammad Waseem Moaz, one of the last remaining paediatricians in rebel-held Aleppo, was killed in an air strike on Thursday.
Charity Medecins Sans Frontieres said the attack on the al-Quds hospital left more than 50 people dead, including at least six medical staff.
But it was Dr Moaz's death in particular that has struck a nerve.
This emotional Facebook tribute posted by a colleague has now been shared more than 23,000 times.
In it, Dr Hatem, the director of the Children's Hospital in Aleppo, praised Dr Moaz's "humanity and bravery".
He said that Dr Moaz, 36, used to work at the Children's Hospital during the day and then attend al-Quds hospital for emergencies in the evening.
"Dr Moaz and I used to spend six hours a day together.
"He was friendly, kind and he used to joke a lot with the whole staff," he said.
"He was the loveliest doctor in our hospital."
Another colleague of Dr Moaz told the BBC's World Tonight programme that they had worked together for five years.
"He was one of my best friends. He was 36 years old, unmarried up until now, waiting for this bloody war to stop to be married", he said.
"He loved his country, he loved his city. He had to stay close to those babies. Who would treat those babies if everybody left?"
Medecins Sans Frontieres, which ran the al-Quds hospital, said Dr Moaz was "one of the last paediatricians in Aleppo". He had worked at the hospital since 2013.
"He kept it going, was always there and always worried about the needs of the people. He was honest and very committed. He worked in conditions you cannot even begin to imagine," MSF representative Aitor Zabalgogeazkoa told the BBC.
MSF said that the hospital was well-known locally. It was hit by a direct air strike on Wednesday.
Aleppo's hospitals are already under extreme strain. Earlier this month Dr Zahed Katurji told the BBC that there were no more than 25 doctors operating in Aleppo.
Local sources blamed Syrian or Russian war planes. The Syrian military has denied targeting the hospital.
MSF said that seven of the hospitals it supports have been bombed since the start of 2016, leaving at least 16 medical staff dead.