The fact that Mr. Vaughan apparently fetched a heater from his vehicle has triggered mention of "gun in parking lot" laws, like Indiana and many other states have enacted.
It is my considered opinion that those laws are entirely about the convenience of CCW holders, in that they allow a person to tote to and from work, but they don't amount to a hill of beans when it comes to stopping a fox that's actually gotten into the chicken coop.
Let me think over some of the last office-type gigs I worked...
There was the one where I was working in the shipping & receiving room of a Fortune 500 company's regional offices: I was in a windowless back room on the twelfth floor of an office tower. If I'd heard shooting and craziness out in the offices, I could have bailed out the service door and headed down the fire stairs... to fetch my gun in the parking garage twelve floors below? Sorry, I left my cape at home today.
The secretarial gig at the scientific equipment company in the office park? If somebody had come in through the front door, he'd have been between me and my car. A pistol locked in the trunk of the Fiero might as well have been on Mars for all the good it would have done. Again, I'd be bailing out the back door yelling "Feets don't fail me now!" like a Looney Tunes character.
At the airport? I had a motorcycle. Where the hell was I supposed to lock the gun? Besides, the motorcycle was parked in the hangar right next to my office door. If I heard somebody yelling "Aloha Snackbar!" over in the FBO and I could get to the bike, my next action would not be to pull a Beretta Tomcat out from under the seat and go face down an unknown number of Kalashnikovs with it. No, I'd be takin' the highway to the danger zone across the taxiways and out the airport gates.
Besides, if I get out to the parking lot and get my gun from wherever it's secreted in the vehicle, by the time I could get back into the building, the first responding officers would be showing up. They'll be amped up, switched on, and looking for a crazy person with a gun running around inside the offices of I.N.C. Inc., and the batteries are dead on my "DON'T SHOOT! GOOD GUY!" beacon.
There's the occasional instance of a good guy running out to safety and then back in to the sound of the guns to save the day, but they are the exceptions that prove the rule. While a gun in the parking lot might be a few minutes closer than the gun in the holster of a responding cop, the fastest response is the gun you have on your person right then.