“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures”
‘Unreasonable’ is the word you are skipping over. The actions were reasonable and necessary.
Although it was not adopted until after WWII, the 4th Geneva Convention recognized that internment of civilians can be necessary. See Art. 42 and surrounding articles, and 83 and following. “The internment or placing in assigned residence of protected persons may be ordered only if the security of the Detaining Power makes it absolutely necessary.”
Ah, you’re now quoting European law to justify actions contrary to the US Constitution?
Even if, for sake of argument alone, I consent to your interpretation of “unreasonable”, you still lack the warrant “upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.” Get that, search away, and if you fine nothing leave the person alone; if you find something appropriately condemning, prosecute accordingly. Taking everything they have, and throwing them in prison (however cushy), requires their day in court.
As it is, the domestic examples in question were (post-attack) discovered to have copious concrete & circumstantial evidence against them, and were being observed for such behavior. We have Constitutional means to handle such before attacks are carried out; seems our Executive branch lacks the will to act thereon.