If the Constitution doesn't apply in these zones, then the Authority of the DHS doesn't either, since their authoirty (in theory) derives from that same Constitution. These zones are therefore Lawless Zones in which you are free to kill DHS personnel as the bullies, thugs, and thieves they are.
If the Govt doesn't follow the laws, there is no reason for the people to do so either. If the legitimacy of thier actions comes from the barrel of a gun, well, we have guns too.