Benton, IL – An Army veteran who authorities say threatened a shooting rampage at a Veterans Affairs hospital in southern Illinois changed his plea today in federal court. Twenty-nine-year-old Mark Harmon pled guilty to a charge of attempted possession of a firearm on federal property with the intent to commit a crime. A sentencing hearing is April 19. Authorities say Harmon was found with a handgun in October outside the Marion VA hospital after calling a nurse and saying he planned to "fill that place with lead." Investigators found a loaded handgun, a magazine and 13 loose rounds of ammunition in Harmon's truck. He's jailed without bond. Many western Kentucky veterans go to the Marion hospital for care.