I know what are you thinking; Blackwater USA, or Haliburton, KBR.
No, the real brownshirts (or one of them) are Infragard a National Security Corporation, established in 1996, from the highest levels of corporate businesses, to do work for the FBI.
The FBI has deputized this Corporation to help out the Government in case of a National Emergency, with the right to use lethal force against potential terrorists.
That may be You, since you don't know which of your neighbors belongs to this organization, to use a national emergency situation as an excuse to eliminate people they don't like.
But read for yourself the juicy stuff at their website!