Review either a national or regional incident of workplace violence.  What were

 Review either a national or regional incident of workplace violence.  What were the causes of the incident?  What was the response from security services personnel?  Were there telltale signs before the incident?  Could any preventative measures have been taken to mitigate the incident from occurring?  Please explain. 
300 Words Max 
BOOK:
Curtis, G. & McBride, R. (2011). Proactive Security Administration, 2nd. Ed.; ISBN-
13: 9780135071502