Actually 3 layers deep of "Gun Free Zones"
Layer 1: Washington DC
Layer 2: Washington Navy Yard, actually walled in. I have been there numerous times. Security was always a pain in the neck but
relatively easy to get just about anything past them (just an observation), assuming that you are authorized to get in. It is generally very safe inside the walls. We routinely worked there late at night & left our trucks open while we moved equipment. Several admirals & their families live there.
Level 3: NAVSEA bldg 197: Most of what NAVSEA does is very Top Secret. Getting into that building requires a properly programmed card key.
Even when I had a contractor ID at the Yard, still needed to get permission & an escort to get into one of the NAVSEA buildings.
Only one possible conclusion: INSIDE JOB
I'm very curious as to the back story on this one, especially if there was more than 1 shooter.