Police were called to the Safeway station, 1815 Baldwin St., shortly before 1 a.m.
The employee told police that a white male came into the store and was making a purchase when he pulled the knife and demanded money from the cash register. The suspect then fled on foot, police said.
A K-9 unit was used to track the suspect, but they lost the track a short distance away from the gas station.
Anyone with information is asked to call the Ottawa County Sheriff’s Department or Silent Observer at 1-877-887-4536.
The suspect was described as being in his late teens or early 20s; about 5 feet, 10 inches to 5 feet, 9 inches in height; and weighing about 170 pounds.