Looked up a little info about the Nation of Islam in Houston where both of the shooters were reportedly members. Look at the anti-white hate propaganda they have on their website that I stumbled onto at their website:
http://lfnoihouston.org/
Their contact info:
Phone: (832) 331-7863 Visit Us At: 3815 Live Oak Houston, Texas 77004 (inside the SHAPE Community Center)
There's some confusion. This is the correct one though I bet the other one listed is probably connected and that their philosophies are very similiar:
https://www.facebook.com/pages/Nation-of-Islam/120288507988667