A 17-year-old assailant opened fire inside a Maryland mall, hitting a 13-year-old boy in the leg as frightened shoppers ran for cover -- and the wild incident was caught on video.

Footage of Friday night's shooting was posted on social media, and it kicks off with people calmly strolling through the Wheaton Mall in Montgomery County, MD. 

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The suspect, dressed all in black with a hoodie over his head, is seated at a table waiting for his chance to strike.  

A bunch of teens then walk past the suspect, who suddenly jumps up and aims his handgun at them, firing several shots. Shoppers can be heard screaming as everyone scatters.

Police said a single bullet struck the 13-year-old boy in his leg. The teen was rushed to a local hospital, where he was treated for non-life-threatening injuries. Thankfully, nobody else was injured.

Cops said the shooter tried to make a break for it, but an armed security guard grabbed and detained him for police, who took him into custody. Charges are pending.

Investigators did not release a motive.