From the NBC News (formerly MSNBC) site just now: "It was not immediately clear why local police were classifying the shooting as domestic terrorism. Federal law enforcement officials told NBC News the suspected gunman had no obvious connection to domestic terror or white supremacist groups and apparently was not on any list of suspected terrorists. The suspect was in his early 40s, and while he had an arrest record, it was for minor offenses, one federal official said." Perhaps he had no direct ties to groups but: "Officials told NBC News the suspect, who served in the U.S. Army, had many tattoos. The suspect had some kind of radical or white supremacist views but, as far as officials said they had heard, he was not in any kind of radical organization." (Please keep Brian Ross off coverage of this.)
A duplex in nearby Cudahy has been surrounded and searched with speculation mounting that this was the slain shooter's home.