Officers were dispatched to the gas station in front of the Super One Foods, 1105 E. Gentry Parkway at 9:37 p.m.
The cashier told officers that a black male displayed a handgun and demanded money, according to a statement from police.
Police are looking for a black male in his late 20s to early 30s, between 5 feet and 5-feet-2-inches tall, wearing a black hoodie or possibly a hooded zipper-type sweater with a gold colored design and blue jeans.
The man is believed to have a tattoo on the right side of his face and gold upper teeth.
Witnesses said he ran north from the area with an undisclosed amount of cash from the business.
Anyone with information about this crime is urged to contact the Tyler Police Department at 903-531-1000 or Tyler/Smith County Crime Stoppers at 903-597-CUFF.