Criminals in D.C. should think twice before unloading their gat on someone. The ShotSpotter is a tiny sensor that's been hidden throughout D.C. listening for gunshots and notifying 5-0 the second it hears them. The sensors are pretty small and can detect gunfire up to 2 miles away pinpointing where the shots were fired. They can even distinguish between gunshots and similar sounds like firecrackers. Cool idea, though we'd still prefer to see some bazooka-carrying robo vigilante.