Yea I was thinking along those lines . not much security for a military set up were 2000 workers are or the guy is military an belonged there .1) Unless the officer killed was one of the gate guards (where the hell was his backup / partner?), the shooter had to be on the grounds.
2) If he was armed and on the grounds, he either belongs there or someone (security) f*cked up big time.
If a lone guy can walk in on a military installation an get to the 4th floor roof or window some one screwed up.