The garage is located across the street from Duke Hospital.
The employee said she approached a man on the sidewalk in front of the garage because he was limping. The man told her he had a weapon and demanded money. Police did not say how much money was taken from the victim.
The suspect fled the scene on foot through the entrance of the garage and was last seen on Erwin Road headed towards Trent Drive.
The employee went into the hospital to ask for help, but she was not injured.
If you have information about the incident, call the Duke University Police Department at (919) 684-2444.