It happened at 8:55 p.m. at the Rite Aid Pharmacy in the 6900 block of Crestwood Boulevard.
Police say two suspects entered the store just as it was closing. They say the two men approached a woman cashier displaying a handgun and demanded money.
The two suspects escaped with an undisclosed amount of cash and cigarettes.
Police say the first suspect is described as a black man in his mid 20s, short with a skinny to medium build, wearing a black and gray stripped hooded shirt, black faded jeans, black gloves, and blue mask. Police say the man spoke with a stutter.
Police say the second suspect is described as a black man is his mid 20s, medium build, wearing a red hat, black long sleeve shirt, white gloves and dark jeans.
Anyone with information regarding this crime is asked to contact Det. Ronald DeMent with the Frederick County Sheriff's Office at (301)-600-2534.