Domonic Billa was shot multiple times in the chest while in the food court of the mall near the orange entrance around 5 p.m., authorities said.
Billa's stepfather is assigned to the homicide/non-fatal shooting unit in the office of District Attorney Larry Krasner.
"I extend my deepest condolences to our Detective, and to the loved ones of Mr. Billa. We are outraged over the violence that claimed the life of this young man," Kranser said.
Billa apparently announced his plans to go to the mall on social media.
In the minutes proceeding the shooting police say a fistfight had broken out among a large group.Surveillance video posted on Instagram shows a man on crutches in an altercation with a man in a red sweatshirt, according to police.
It didn't take long for the the fight to turn from fists to guns.
A video of the moment the shooting started was posted on Instagram.
People running from the scene report being trampled, and many suffered bruises and broken bones.
"Workers inside the mall, the mall is very large, locked themselves down inside so we had our K-9 and SWAT team go through the entire mall one business at a time to make sure that the shooter was not on location," said Philadelphia Police Sgt. Eric Gripp in a statement to the press.
The mall remained closed for the rest of Monday night and reopened on Tuesday.
Anyone with any information on the whereabouts of the shooter is asked to call police at 215-686-TIPS.
Click here to follow Daily Voice Lower Paxton and receive free news updates.