A base full of soldiers. Many of the them combat veterans. Unarmed by laws and regulations. A
gun-free target rich environment for the one guy for whom laws and regulations make no difference.
And how did it end? It ended like it always does. When good guys with guns showed up, it was over.
The shooter should have gotten off exactly one aimed shot before everyone else in range had engaged him. There would be a lot less dead and wounded.
Arm the good guys. Because otherwise this will just happen again. We are in a situation where soldiers are being killed on bases because politicians decided that guns were too icky and scary for soldiers to carry.