The jury found Flora guilt on three counts -- first-degree murder of Endia Martin, as well as attempted first-degree murder and aggravated battery with a firearm involving another teen who was the intended target.
Flora's pre-sentencing date is scheduled for Feb. 26.
Flora's now 16-year-old niece is awaiting trial on murder charges in juvenile court. The niece, who remains unnamed because of her age, asked her uncle for a gun to take to the fight.
Joel Brodsky, Flora's attorney, said in a statement: "Anytime you have an autopsy picture of a dead 14-year-old girl go with the jury into deliberation ... it's going to be a difficult case."