Two were injured in the shooting at Hoover's Riverchase Galleria on Thursday night, an 18-year-old man and a 12-year-old girl, according to CNN.
It's believed the gunfire broke out following an argument between the 18-year-old and the 21-year-old. The older man shot the younger one, NBC News reported, then ran. He was later killed by a Hoover police officer.
The 18-year-old man was struck twice in the chest, according to police, and is listed in serious condition. It's not clear how the 12-year-old girl was hit, but she is alert and underwent surgery to treat the wound, police said.
Witnesses described hearing a barrage of gunfire at just before 10 p.m. local time on Thursday. The mall was open late for early Black Friday shopping.
Last year, the same mall was shuttered early on Thanksgiving after a fight erupted between two women.
Police said the mall will remain closed until further notice.