The incident took place at the Riverchase Galleria in Hoover as shoppers began looking for Black Friday deals.
Hoover police said a fight broke out between two teenagers inside the mall near the Footaction store and resulted in an exchange of gunfire, WTVM reported.
One of the teens, an 18-year-old, was injured and the other tried to flee but was confronted by Hoover police, the television station reported.
"One of our Hoover officers did engage that individual, shot him and he is dead on the scene," Cpt. Gregg Rector said at a news conference.