How about pulse sonar of some sort that is so detail-oriented it can detect gun shapes and alert authorities. So in a school, every half hour -- or even based

How about pulse sonar of some sort that is so detail-oriented it can detect gun shapes and alert authorities. So in a school, every half hour -- or even based on motion detection -- some sort of pulse goes out to detect gun shapes. Could technology for that be developed? Is that even possible? Just an idea.. If I were to guess, SONAR is currently very imprecise for something as small as a gun. But what if you had hundreds of SONAR pulses from different locations? Or what if you had many thousands of different analyses run on it?