Close enough to FFX, plenty of people live in FFX and work in Loudon. Lots of emergency vehicles on Broderick Dr. (near Waxpool) in LoCo in the Dulles area.
https://www.google.com/maps/place/Broderick+Dr,+Sterling,+VA+20166/@39.0027944,-77.4501611,17z/data=!4m2!3m1!1s0x89b638c2a0a3cb93:0x2912db99e95df084
I heard that they found a dead body in a mini cooper, and hazmat was there due to "some kind of chemical." Does anyone else know any more details?