Troopers from the Kiski barracks say the suspect dressed in black entered the Export Laundromat about 2:10 a.m. Sunday and demanded money from an attendant who was servicing equipment there.
When the 50-year-old employee told the suspect he didn't have any money, police say the robber pulled a handgun from his pocket and told the worker "he was serious."
Police say in a news release that's when the attendant told the suspect "that he, too, was serious and that he did not have any money."
The suspect ran away after searching the premises and finding no money.
Police haven't made an arrest or released the suspect's name.