A quick thinking clerk apparently foiled an armed robbery attempt at the Stag Oil filling station on East Pershing Thursday night. Police Department spokesman Sgt. Rob Dafoe says the robber entered the filling station shortly before 10pm and pointed a gun at the clerk. However, the employee was able to retreat into an internal  office and lock the door. The clerk reports he then heard the gunman leave through the front door and drive away. The would-be robber is described as being 5'7 with a slender build, wearing a black ski mask and black clothing. Dafoe says that while the clerk's actions turned out well in this instance, police generally recommend complying  with an armed robber rather than risking serious injury or death in such a situation. Dafoe says the case remains under investigation.