Thinking about this more ... 6:00 PM is 18:00 ... how about 17 = 5 PM EST or the last watch ?
Secret Service with long duffle bags and badges marked United States Secret Service Special Operations Counter Sniper Team heading into the Ronald Reagan Presidential Foundation and Institute building a block north of White House.
https://mobile.twitter.com/FordFischer/status/1269295500106366978
This one, 4:49 or 16:49 EDT (15:49 EST)?