There's not many I know of, but I decided to list a few I know. Feel free to share any others you know of.
2016 Ohio State Attack
2006 University of North Carolina attack
July 22, 1997 terror attack in Israel - Terrorist rams car into group of teenagers then stabs them with a knife. Source: Listed on this page
"Now! Feel death, not just mocking you. Not just stalking you but inside of you. Wriggle and writhe. Feel smaller beneath my might. Seizure in the Pestilence that is my scythe. Die, all of you."
- T.J. Lane (in his Facebook poem)