SOMERSET, Wis. -- A teenager in western Wisconsin has built a device that could save lives in the event of an active shooter situation. WCCO reports that Justin Rivard, a senior at Somerset High School, came up with the idea after noticing a potential flaw in the school's emergency response plan. The 'Justinkase' lock is made with two steel plates cut to a specific shape. Handles are welded to them, and a rod and tube are welded on to connect the end place. Finally, a locking knob is added.