Brown has apparently apologized to the team, not sure what will happen next. I honestly hope they suspend him for 4 games without pay.
ESPN:
A Raiders source confirmed Brown was unhappy with the fine levied by the team and, seeing Mayock watching practice, walked over and initiated an exchange with the GM. The Raiders source confirmed information from another league source who said Brown called Mayock a "cracker" and unleashed a barrage of "cuss words" during the altercation.