The federal government recommends you bring scissors to a gunfight.
The Department of Homeland Security offers Americans tips on how to survive an attack by an “active shooter,” including “throw[ing] items” and grabbing a pair of scissors.
DHS recommends Americans either “evacuate” the building or “hide out” depending on the situation, according to a 2008 handbook and “pocket card.”
But the third option, “take action,” is considered a “last resort” by the government.

One can “attempt to incapacitate the shooter” by “act[ing] with physical aggression and throw[ing] items at the active shooter,” suggests DHS.
A web video released by DHS in January says, “you might consider trying to overpower the shooter” as a last resort, “with whatever means are available.”
The clip shows an office worker grabbing a pair of scissors for the purpose of “trying to overpower the shooter.”
http://www.youtube.com/watch?v=oI5EoWBRYmoThe DHS materials never recommend using a concealed firearm to disable or kill the assailant, though the option would clearly be more effective than throwing scissors.