By CBS3 Staff

PHILADELPHIA (CBS) — A teenager was shot in the legs on a SEPTA subway platform in Center City on Monday afternoon, officials say. It happened at the 15th Street Station along the Market-Frankford line around 3:20 p.m.

Philadelphia police say the shooting stemmed from an altercation between a 19-year-old man and the suspect.

The victim was transported to an area hospital with non-life-threatening injuries after he was shot in the legs.

Police say they know who the alleged gunman is, but they have not yet arrested him.

Officers saturated the Dilworth Plaza, as K-9 dogs combed through the planters and bushes searching for evidence.

Witnesses say they’re breathing a sigh of relief this wasn’t a mass shooting.

“Especially in this day and time of mass shootings, you hear a gun and people shooting downstairs, the first thing that came to my mind, is this dude coming upstairs, is he a terrorist?” Clayton Marshall said.

It’s unclear whether the shooter and the victim knew each other.

Market-Frankford line trains are operating with residual delays following the shooting.

Stay with CBSPhilly.com for this developing story.