It shortly after 8:30 p.m. when the masked suspect entered the Speedy Mart located in the 1100 block of South Broom Street.
Surveillance cameras show the suspect approach the counter, pull out a black handgun and demand money.
After obtaining an undisclosed amount of cash, the suspect fled the store northbound on Broom Street.
The suspect is described as a black male, 5'5" tall, 150 pounds and was last seen wearing all dark colored clothing.
Anyone with information about the identity or whereabouts of the suspect is asked to contact police.