Police say the man followed a customer inside the store from the gas pumps on the west side of 711 and when the customer went up to the counter to pay for gas, pointed a gun at the customer and clerk and demanded money, "or else he was going to shoot".
Police say the man took money from both the store and the customer and ran away toward Timbers Apartments.
He's described as possibly a white male, wearing a hoodie, and either a mask or a scarf over his face.
If you have any information that could help investigators, just call crime stoppers.
You won't have to give your name, and the information you provide could earn you up to $1,000.
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