I would add that it seems unlikely that he initially intended only to kill his girlfriend and then esacape.
He brought two weapons and enough ammunition to do exactly what he wound up doing - methodically killing dozens of people.
If he intended to pull a hit on his girlfriend and escape, he was not packing light for such a surgical mission.
Nor did he appear to have a vehicle handy to escape in.
I doubt he ever intended to survive the day.
Now THAT would be a major screw up in my opinion and changes the dynamics of the entire response and I’ll have to completely change my position on the official decision-making team.