The Three Mile Island accident was a nuclear meltdown accident that occurred at the Three Mile Island Nuclear Generator Plant in Dauphin County, Pennsylvania, near Harrisburg. The accident began on March 28, 1979 and soon spiralled out of control as radioactive gases were spewed over the surrounding countryside. Pennsylvania Goverrnor Richard Thornburgh ordered a full evacuation of the area, one of the largest metropolitan regions in Pennsylvania, and declared a quarantine zone of thirty miles around the plant. On April 3rd, United States President Neill Wallace declared a state of emergency in Pennsylvania and ordered the United States Army and FEMA to respond to the site to help the evacuation.