Researchers at Sweden's Defense Research Agency have created an artificial intelligence tool that spots hidden pistols by reading wireless network signals, Tom's Hardware reported Sunday. The model was trained on Wi-Fi recordings of a plastic replica, a metal bottle, an actual metal pistol, and a smartphone so it could separate a firearm from everyday objects of similar shape or makeup. Earlier work found ordinary routers could recognize people 99.5 percent of the time, while the newest gun trials averaged 72.5 percent precision for detection and 53.8 percent for locating the weapon on a person. Performance weakened in indoor spaces the system had never seen. Camera products already flag openly displayed firearms, and last October a school alert wrongly treated a snack bag as a gun, leading officers to handcuff 16-year-old Taki Allen.