Following 9/11, we witnessed the revengeful murders or beatings of several innocent people, who just happened to share the same ethnicity or religion as the hijackers. Regarding Virginia Tech: I hope that doesn't happen this time 'round.

Anyone who did that would be as guilty as the original perpetrator. Good point.
Do not confuse that concept with the proper and correct connection to a well-founded radical-Muslim based effort of jihad in certain cases of terrorism.
This,however, was not one.