Why we should be concerned about domestic drones

LET’S imagine the worst-case scenario involving domestic drones. No, not the tiny quadcopter whose operator mistakenly crashed it on the south lawn of the White House. Let’s try something scarier.
Take several drones, and equip each with a few pounds of explosives, shrapnel, and ball bearings. Then send them on a one-way kamikaze mission. As the technology advances, network the drones so they travel in a group and explode at the same time. How do you stop them?