SIOUX FALLS, S.D. (KELO AM) - Police say a Sioux Falls woman used a stun gun on a knife wielding man last night at the Gas Stop on West 41st Street. Officer Sam Clemens says the 26-year-old woman was getting out of her car when the lone male approached her. Clemens says the suspect told the woman that he knew her but she didn't recognized him. He pulled out a knife and threatened her with. She produced a stun gun and fired it at him. He fell to the ground, she took his knife and drove to the law enforcement center to report it to police. Clemens says the man was gone when police arrived. He says the victim gave a general description and investigators hope the store's video surveillance captured the suspect's image.