This situation happened to me last year.
Let me give you some orientation. There is a Kroger right near where I live. It's one of the larger ones. Just in front and off to the left of the Kroger contained in the same parking lot-system is their Kroger Gas Station. Just off to the left of this is a drive-through Chase ATM on the same tarmac.
I needed to get some cash one evening, so I drove out to the ATM and waited for the car in front of me to finish. While I was waiting, I saw two "gentlemen" loitering behind the gas station out of the light of the tarmac. I pulled up and started my transaction. I was waiting for the cash to dispense when I saw the two gentlemen making a B-line for my car at a brisk walk while looking around them (about 50 feet away); the standard (is anyone going to see this...) motion. I pulled my weapon to my lap (I seat carry when I'm alone) and grabbed my cash just as it dispensed and hit the gas when they were about 20 feet from me. I looked back and saw them both make the (Aww man!) big arms motion. I re-holstered my weapon and put it IWB while I pulled into Kroger and did my shopping.
After shopping I realized that I did in fact need gas. I drove on over to the Kroger gas station and got out to fill up. I swiped my card and began looking around now on the well-lit tarmac. I didn't see anyone but the teller in the booth. I start to fill up and then here they come from around the back of the building- the two guys (~80feet).
"Hey man let us holla at-chou..." These guys really mean no good, and I know it. I honestly know that their intent was to rob me right at the ATM before, and they know that I probably still have cash on me.
I crossed in front of the teller booth (must pay at the booth after hours), made serious eye contact with the 18yo teller and said loudly "Call the police." I didn't know quite what we would need them for just yet, but in my head, I know they are going to need to be called.
I turned toward these two guys (~35-40ft) and tucked my shirttail behind my Glock 19 at 4 o'clock, and kept my hand there. I then gave both of them a hard dose of eye contact and they stopped moving. I said, "The cops are on their way. And I'd be running if I were you."
They looked at each other for a few seconds then turned around and jogged to their POS car at the back of the lot, got in and sped off. I told the teller that they were gone and he told me, "I really thought those guys were going to rob me earlier."
Cops came and talked and promised to make a few more sweeps by there the next couple of nights.
I drove the 3 blocks home and as soon as I walked in the door I could feel my heart pounding in my hot hears and I don't think I stopped sweating for about an hour.
I'm pretty proud of our LEO community where I live. They're some of the kind that really like to help out the average Joe, and they seem to support gun rights. I really think that being armed gave me the confidence to stop a mugging, robbery, and God knows what else. I didn't even have to pull my weapon, but just the knowledge that I had it gave me what I needed in order to act.
For the record, my personal perscription for dealing with midnight punks is the police on the phone and a gun on the belt. This one in particular turned out pretty well for everyone, bad guys included. And at the end of the day, I think that's the goal. No crimes committed and everyone in their beds.
~LT