No surprises for most people on this forum about the need to be able to protect oneself, but here is an interesting article on a shift in the thinking on active shooter response by law enforcement.
http://www.nytimes.com/2013/04/07/us/in-a-shift-police-advise-taking-an-active-role-to-counter-mass-attacks.html?ref=ericagoode&_r=0
http://www.nytimes.com/2013/04/07/us/in-a-shift-police-advise-taking-an-active-role-to-counter-mass-attacks.html?ref=ericagoode&_r=0