Police Chief Desiree Kershner said the station on Highway 45 was held up shortly before 7 p.m. by a light-skinned black man wearing a hooded sweatshirt and gloves.
She said he was holding a semi-automatic handgun and a crowbar.
He allegedly held the gun on the clerk and demanded the clerk use the crowbar to pry open the ATM machine. The clerk had a key to the ATM machine, opened it and the reported robber took about $2,900.
The man ran away toward Nettleton where police believe he got into a vehicle.
The clerk was unharmed.