DC Navy Yard's Marine Barracks soldiers had their weapons ready... but no ammo???

[MikeK]

Murderers pick places where they know their victims will be unarmed.

Bullshit. I can think of a thousand other locations where it is more likely the victims would be unarmed than at a military installation.

The shooter picked that target for an entirely different reason. In fact, he may have been counting on being shot to death.

Good chance you are absolutely right. Many (most?) apparently random, unprovoked homicides are suicides turned outward. Just as many violent suicides are homicides turned outward.