There was such a case in my neck of the woods back in the late 1800's.

Strikers from a coal mine near here had blocked the road and the rail road and were not allowing the trains to pass. The US Marshal for this area sent a telegram to the US Attorney General and asked for troops to blast them all to kingdom come if they did not cease their blocking of the railroad since the US Mail could not pass through.

The Attorney General told him to let the strikers know they needed to disperse. If not troops would be sent and the strikers could deal with the troops. No one had the right to shut down ANY federal situation and the troops would understand what needed to be done.

The strikers, who were armed to the teeth, decided to continue their strike but the occupation of the railroad was over with-in the hour.