The Hoover Police Department said the scene is now secure.
The mall, located in the Birmingham suburb of Hoover, reopened at 6 a.m. Friday, a Riverchase Galleria mall security officer said.
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. The 12-year-old girl had to undergo surgery. Police say the suspect shot an 18-year-old man after an altercation around 9:30pm.
Capt. Greg Rector said in a news conference a 12-year-old girl struck by gunfire was hospitalized. She was transported to the Children's Hospital of Alabama where she is in stable condition.
Management at the mall said it would be closed until further notice.
This story corrects dead man's age to 21.
All were advised to avoid the mall area at this time.
The officer who shot the gunman has been placed on administrative leave while the Jefferson County Sheriff's Office investigates the shooting. Hoover, Alabama police say an officer shot and killed one teen, who had shot and injured another teen. The mall was open late for early Black Friday shopping. "And are grateful for their swift action to contain the situation".
The City of Hoover tweeted that police had the incident under control.
"You just don't bring guns into a crowded mall", he said.
Ask yourself this, is getting up super early or staying up late worth dealing with insane people who will some cases, fight you over a T.V. or PS4?