What law enforcement agencies are under the aegis of the Dept. of Homeland Security? How many of those employees are armed?
FBI, US Marshall Service, ICE, Federal Air Marshall Service, Secret Service, Layered Nuclear Defense Agency, National Fugitive Operations Service, Protective Investigation Service, Diplomat Security Service, US Coast Guard...etc.. There also is the Federal Law Enforcement Training Center in which many State and Local law enforcement agencies receive training. (..and those are just the agencies/departments that I can recall that have armed employees).
Hell, these days the milk inspector carries and has full tac gear in the trunk. Them Swede dairy farmers can get fractious, dontcha know!