[Scan-DC] Arlington motorycycle-cade?

[Clegg, Andrew W.]

A "motorcade" of what appeared to consist of about 25 - 30 Arlington
motorcycle cops with lights and sirens going, followed by a single white
unmarked cruiser with lights and siren, just went through Ballston,
heading west on Wilson Blvd. I did not see them actually following or
escorting any other vehicles, but it's possible that something went by
first without making much noise, followed by all the motorcycles.

Any ideas what this is all about?

(I don't have my digital scanner with me so I can't listen to anything
other than the main dispatch channel, which did not have any traffic
about the motorcade).