UNDATED (CNN) -- We're learning more about the alleged shooter in the deadly rampage at a Sikh temple near Milwaukee Sunday.
Wade Michael Page, 40, was an Army veteran who the Southern Poverty Law Center had been watching for years. The agency says Page is well known to white supremacist and other hate groups.
Mark Potok with the Southern Poverty Law Center says, "This man has been in the thick of the white supremacist scene in this country for a good dozen years now. We've been tracking him for over 10 years. He has played in some of the most infamous white supremacist rock and roll bands in this country."
Page allegedly killed six people and wounded four others in Sunday's attack. The suspected lone gunman was shot to death by police responding to the scene. The FBI is trying to determine if the shooting was an act of domestic terrorism.