The incident occurred at approximately 6:15 p.m. Wednesday at the Subway in the Whiteland Towne Center shopping center.
Police say a woman was eating with her 9-year-old daughter when a man approached her and demanded her purse.
The woman refused to give the man her purse.
The suspect then brandished a handgun which he stuck against her body.
The victim turned over the purse and the suspect fled from the restaurant.
He is described as a white male between 30 to 40 years of age. He is approximately 5'8" tall and weighs about 175 pounds. He was last seen wearing dark pants and a dark hooded sweatshirt.
Police have released a composite sketch of the suspect which is shown above.
Anyone with information on the incident or the suspect is asked to contact the West Whiteland Township Police Department at (610)363-0200 or (610) 692-5100.