A tragic end to a gaping hole in security

The last time I was in the capitol back in the late 90s, I was struck at how easy it was to just walk into the capitol without anyone even looking at you sideways, and there were all these powerful people walking around. Yet at every professional job I've had, there were security check points. And the guards at these checkpoints carried guns. That's what makes this story so tragic. The guards who was shot at the state capitol was unarmed and stood no chance. In fact, the guards never carry guns there. If this guard had seen the man walking up to the capitol waving a gun around, what was he supposed to do? Sit there and wait for the bullets to fly? Hide? Put up some velvet rope across the door and hope for the best?