It happened Christmas Day at the Corner Market on Lamar near McLean, while owner Mohammed Ibrahim was behind the counter.
He says the teen told him he forgot his phone in the store and wanted to watch surveillance video to see if anyone took it.
"So, I gotta lock the store, go inside and watch the camera for him," Ibrahim says, "I told him I need somebody to help me to do that."
Because he was working alone, Ibrahim asked the teen to come back in the morning. Ibrahim says the teen refused and started making threats when he couldn't see the video right then.
"If I don't do that, he gonna shoot all the customers. He gonna rob the customers, each one coming in here," Ibrahim says.
There were some tense moments but thanks to the teen's mom, he finally calmed down.
"His mama came in and took him out. (She said) Mohammed, he don't play. He's going to call police on you," Ibrahim says.
And Ibrahim did call police but the teen was gone by the time officers got there. Police are still looking for him.
"You got to have some respect for customers, for the people, for the business, not threaten and pull out the gun. I don't think that's the right thing. He deserves to go to jail," Ibrahim says.
Ibrahim is thankful no one was hurt.