British doctor Isa Abdur Rahman was killed Wednesday when the makeshift Syrian hospital where he was working was shelled.
The 26-year-old graduate of Imperial College London had put his career on hold and traveled to Syria to treat injured civilians.
Chairman of the charity Faddy Sahloul called the doctor "one of the bravest and most dedicated people I have met."
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"I was very close to Dr. Isa, a shy young man whom I first met two years ago. We spent a significant amount of time working together in Turkey and Syria and he was one of the bravest and most dedicated people I have met," said Sahloul. "Everyone who knew him is shocked and saddened to hear the tragic news of his death, but we can draw comfort from the fact that he died doing work that he loved. Our thoughts and prayers are with his wife and family at this difficult time."
Two other civilians were killed in the attack and two were also wounded. Hand in Hand for Syria blamed the shelling on government forces.
Friends of Rahman have set up a JustGiving fundraising page to raise money in his name. The initial target was 7,000 pounds, but the current total of funds raised is 25,575 pounds, enough to build a field hospital in Homs named after Rahman.