Much like 45 Auto said, I work for the federal government, weapons are prohibited, and they do sometimes do searches of cars when entering. On the brighter side, people do need proper ID and a legitimate reason to enter the installation, so random nutcases won't get in.
We do get "Active Shooter" training every year, but it avoids mentioning the one best thing you can do to avoid becoming a victim of an "active shooter": having a gun of your own.
PS - I hate that new term, "active shooter". How about "active murderer" instead? To me and most of us here I think, an active shooter is someone who goes to the range at least once a week.