According to the inside sources of @TrueFactsStated on Twitter (which have been pretty solid thus far, and I'm posting this image of the compiled Tweets, as they were six separate ones, non-threaded, so saving a ton of extra links - originals can be found here:
https://twitter.com/TrueFactsStated):

Now, from what I can tell, the MOE refers to a Marshal's writ of execution, which generally applies to asset seizure, although other legal professionals have commented on these Tweets that it could involve arrests, as well.
Also: Any indictments issued here are sealed, so there are no names. There's no indication that Trump himself, or any of his inner circle, are implicated here. But since the indictments are sealed, there's no indication that they're not, either. The days and weeks ahead will reveal more, but a lot of it won't be fully known until the indictments are unsealed.
Edit: Analysis from one attorney:
https://twitter.com/lauferlaw/status/864953607183101955Quote
FBI or federal Marshals plan to apprehend defendants has been approved by the court and their executing warrants per @TrueFactsStated
This post was edited by Surfpunk on May 17 2017 04:08pm