BROOKLYN - A teenager is behind bars after he allegedly caused a small explosion inside a Bed-Stuy subway station. 

According to police, 16-year-old Keyshawn Brown ripped a metal sign box and glass from an A train and tossed it onto the tracks at the Nostrand Avenue stop last Thursday. 

They say Brown then stood back and took video as a C train came into the station and struck the metal sign. 

Brown is charged with criminal mischief, arson and reckless endangerment.