Long time ago, in a galaxy far far away I was on a receiving end of this because of one of the customers that we had. We went through an extensive training, including direct meetings with people from USAO. The bottom line of those instructions was :
* there are too many entities that may think they can get this information
* you are to ignore them all, execute a physical intrusion protocol (lock every and make everything inaccessible ) and notify your contact at USAO.
* our legal signed off on it.
We have executed intrusion protocol four times during my time there. In one case it involved a dick waving contest between state police and state court and USAO, USMS and federal court.
The bottom line, learned in trenches, is that if you are a reasonably big fish, you classify all search warrants as intrusions and deal with them as you deal with other physical intrusions. Documents/data will be turned over in an orderly fashion by your legal.