Authorities in Marshall are offering a $500 reward for information on an alleged armed robbery at a Marshall convenience store. A white man is his mid-twenties reportedly entered the Cenex-Ampride store in Marshall on Tuesday and demanded money from the clerks while brandishing a knife. The man got away with an undisclosed amount of cash, but no one was injured. The suspect is reportedly five-foot-ten, with facial hair and a medium build. Anyone with information on this crime is asked to call (507)537-7000.