The source identified the teen as Mohammad Shaar.
Social media sites circulated a photo of Shaar and three of his friends taken shortly before the explosion. Posing for a group selfie, the teens can be seen meters from the rigged golden Honda CRV used in the attack.
Shaar and his friends Omar Bikdash, Rabih Youssef and Ahmad Moghrabi, all secondary school students, were at a park nearby enjoying a sunny Friday morning at the time of the explosion.
Moghrabi, Youssef and Bikdash survived the blast while Shaar was transferred to the American University of Beirut Medical Center after suffering serious head wounds.
Friends of Shaar spent Friday night at AUBMC praying for their friend’s well-being.
With Shaar’s tragic passing away, the death toll from the bombing rose to seven, the security source said. Shatah, his bodyguard, and four other people died on the day of the explosion. Seventy people were also wounded in the blast.
Shatah had been headed to a meeting of the March 14 coalition that was under way at the Downtown Beirut residence of former Prime Minister Saad Hariri.
The scene of a massive reconstruction project after Lebanon’s 1975-1990 Civil War, the area targeted by the explosion is a luxurious residential and commercial district and includes several upscale hotels. Friday’s was the first explosion to target the heart of Beirut Downtown since its renovation.