Residents of Beirut have been left in shock after two devastating blasts killed at least 137 people and injured about 5,000 others on Tuesday. Dozens are still missing.
Lebanese authorities said the explosions were caused by 2,750 tonnes of ammonium nitrate stored unsafely in a warehouse.
Charbel Matar told the BBC that his family home was devastated during the disaster, and his brother and friend were treated for injuries.
The explosions happened as Mr Matar was getting ready for work at the American University, where he is chief fellow of haematology-oncology at Beirut Medical Centre. After the shockwave caused the building to collapse, Mr Matar fled outside with others in the centre.
"I looked to the sky and I saw this mushroom effect, this big explosion and it looked like it was coming from downtown.
"The first thing that came on my mind was my family, my friends, my brother, my fiancé. I video-called my mum, it was the only thing that would connect and I saw her with my dad. They were alive, there was a little bleeding but they were alive. I tried to call my fiancé - she was working in Beirut but had left 30 minutes before.
"Next I was trying to reach my brother who was at our family home with his friend, which is 5-10 minutes away from the explosion. I was not able to reach him. I tried a few times but I couldn't reach him until he called me and said he was fine. He had some injuries but his friend who was next to him was heavily injured.
"I was in a dilemma. I should stay in the hospital and help my friends, but at the same time I should be with my brother because no one was there. I started to walk to my house which is about 30 minutes away from my workplace. I tried to see if someone could pick me up because my car was heavily damaged and I could not use it.
"Someone did drive me closer to my house, and then I had to walk from the terrifying explosion to my house and tried to get help and transfer my injured friend and my brother to the hospital. I rang around to try and find a hospital because the two hospitals closest to the house were also completely destroyed.
More on the explosion in Beirut
"When I arrived home someone - I don't know who, I'm thankful to him - was able to pick them up by his car and try to get them to [hospital]. This stranger was driving them from emergency room to emergency room because the hospitals were out of capacity. The only hospital that could accommodate them was half an hour away.
"Yesterday we started to try and secure our house. Our house was all damaged and nothing remained; all the windows, all the doors - everything. All the building that we live in - it's a building of seven floors - is all damaged. There are no more windows and the doors exploded; they are all down. There was damage and there was blood.
"We're still in shock; we're still refusing to believe that something happened. We still think it's like a dream or something. It was terrifying. It was horrible."