Here's a list of some of the nation's mass shootings, the apparent targets and the motivation:
1. McDonald's, 1984 - white guy, anti-government, survivalist, appeared to target Hispanics during the shooting: [ame="http://en.wikipedia.org/wiki/San_Ysidro_McDonald%27s_massacre"]San Ysidro McDonald's massacre - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:James_Oliver_Huberty.jpg" class="image"><img alt="James Oliver Huberty.jpg" src="http://upload.wikimedia.org/wikipedia/en/thumb/5/5b/James_Oliver_Huberty.jpg/200px-James_Oliver_Huberty.jpg"@@AMEPARAM@@en/thumb/5/5b/James_Oliver_Huberty.jpg/200px-James_Oliver_Huberty.jpg[/ame]
2. GMAC, 1990 - black guy, upset because his Pontiac had been repossessed. Known to have a temper but kept to himself. [ame="http://en.wikipedia.org/wiki/GMAC_massacre"]GMAC massacre - Wikipedia, the free encyclopedia[/ame]
3. Luby's, 1991 - white guy, disgruntled, loner, angry with women and his town:
http://www.chron.com/life/article/Shooting-rampage-at-Killeen-Luby-s-left-24-dead-2037092.php
4. Famous Univ. of Texas massacre, 1966 - white guy, failing student, previously court martialed marine, brain tumor, into firearms: [ame="http://en.wikipedia.org/wiki/Charles_Whitman"]Charles Whitman - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Whitman1963.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Whitman1963.jpg/220px-Whitman1963.jpg"@@AMEPARAM@@commons/thumb/1/16/Whitman1963.jpg/220px-Whitman1963.jpg[/ame]
5. Post Office, 1986 - white guy, disgruntled loner into firearms, angry with his boss:
http://digital.library.okstate.edu/encyclopedia/entries/E/ED003.html.
6. Law Office, 1983, white guy (Italian American), disgruntled, financial problems, angry with former lawyer.
http://www.nytimes.com/1993/07/03/us/the-broker-who-killed-8-gunman-s-motives-a-puzzle.html
7. ESL Labs, 1988 - white guy, stalker, angry at/obsessed with stalking victim. [ame="http://en.wikipedia.org/wiki/Richard_Farley"]Richard Farley - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Richard_Farley.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/en/thumb/b/b9/Richard_Farley.jpg/220px-Richard_Farley.jpg"@@AMEPARAM@@en/thumb/b/b9/Richard_Farley.jpg/220px-Richard_Farley.jpg[/ame]
Of course, we all know of the famous school shootings in Colorado, (white guys, loners), Virginia teach, (Asian guy, loner), the mass shooting at Fort Hood (Arab guy, angry at America, the war, disciplined at work) and the massacre in Arizona (crazy white guy).
It seems that the majority of mass shootings not involving gang activity, or other crimes, involve loner white guys, or otherwise nutty loners. I don't think we can characterize it as a "hate crime" in the typical sense of the law, or due to an anti-American mentality, usually.
I think these are often just slightly crazy or really crazy guys who never amount to what they think they should, who expect much more than they have and who lash out like babies when faced with life's hardships, instead of persevering like the rest of us do, no matter what, despite the odds.