[USNBandit]

If you look at these two guys, they look like they fell out of the 5.11 catalog. They look like poorly dressed undercover Feds.

[Half Vast Conspiracy]

Fox is talking like it is these two...

[ltc8k6]

More of them in the lower left. Black over khaki with khaki boots. Backpacks. One more in front of ATV.

http://i.wp.pl/a/f/jpeg/30993/Boston_Marathon_Explo_Piot_1_.jpeg

CST - Civil Support Team. Black over khaki with khaki boots.
National Guard Unit.

http://darkroom.baltimoresun.com/wp-content/uploads/2013/04/REU-ATHLETICS-MARATHONBOST.jpg

http://en.wikipedia.org/wiki/Civil_Support_Team