I've seen Russian soldiers successfully shoot down drones using shotguns, the problem is that the smaller ones can be too fast and nimble for humans to reliably target. Even if you can shoot down 2 of 3, the third one will get you.
Combine the YOLO algorithm with a high-frame-rate camera, a two-axis servo, a heavy tripod, and a shotgun... and you're defended!
This could be mounted on the back of a tank or humvee also.