According to Click 2 Houston, Smith and his cousin had found the gun earlier in the day and were at an apartment around 1:30 p.m. when Smith began taking photos of himself holding the weapon.
"It's the worst feeling in my life," the victim's uncle Eric Douglas told the news station.
"It's a numb feeling. It's still unbelievable. Yesterday was my birthday and he came to wish me happy birthday, and now this kind of news," Smith's grandmother Alma Douglas said.Police said Smith believed the gun was unloaded at the time.
No charges have been filed.
Family members told the news station that Smith was set to start college on Wednesday (today) and that he leaves behind two young children.