Re: This LEO is LUCKY!
Without knowing the full story, it's hard to make a judgment.
It could be that the cashier was buying the gun on a layaway plan from the young man and was making his final payment.
When the cop walked in, the presumed innocent citizen feared that the police may misconstrue the situation and suspect an armed robbery was in progress, thereby endangering himself, the cashier, and possibly others in the store.
Therefor, he attempted to conceal the weapon and walk out, planning to complete the transaction at a later time.
The police woman is obviously a regular customer of the convenience store and the cashier likely knows her. He probably said, "That was Lafanso. He's the guy I was telling you about. The one with the great deals on cheap pistols."
The cop, looking for a great deal on a pistol, ran after Lafonso.