"...shooting down the drone is less disruption than closing the airport and flights."
It's also extremely difficult if not well nigh impossible, especially in the dark as it was when this business began last night. To effectively "Shoot down" a drone flying at a few hundred feet a rifle would be necessary (accompanied by an extremely accomplished marksman). A shotgun, even with heavy gauge shot or slugs, whilst requiring less accuracy, would not be effective enough to disable a drone at much beyond about 150 to 200 feet. It ain't really as easy as it seems to be on the telly!