Exactly right. The only Constitutional provisions I can find that even vaguely seem to refer to a restriction of rights in emergency situations are:
The privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it. -- Article I: Section 9
No Soldier shall, in time of peace be quartered in any house, without the consent of the Owner, nor in time of war, but in a manner to be prescribed by law. -- Amendment III
Obviously neither of these has anything to do with either seizing guns or any broad "martial law."