My full answer is as follows
I tell the clerk to call 911. I point my weapon system at the ground but at the ready and observe any conveyance the suspect gets into making note of make/model and any plate info I can see without leaving the store. When the suspect is out of sight I holster my weapon and tell the employee to lock the door until the police arrive, I then write down everything I observed about the suspect and wait for the LEO's.
In other news, our infosec people have gunfightercast.com blocked at work, what kind of !&#* is that?!
Thanks again for your service to our country at your day job and your service to the gun community in your spare time.