Rapid advances and decreasing prices for facial-recognition artificial intelligence technology, fueled by an arms race of surveillance firms eager to dominate the educational market, have made systems that promise to end school shootings faster, cheaper and more available than ever. For schools with high-resolution digital cameras activating face recognition can be easy as installing new software. Trevor Matz, the chief executive of video system BriefCam, said there is increased interest in cutting-edge surveillance technology, including from schools. His company makes software that can recognize faces and filter video with search terms like "girl in pink" or "man with mustache," shrinking hours of footage into seconds. "Everybody we demo the product to immediately goes, 'Wow' and says, 'I want it.' There's not a lot of selling that needs to be done."