You may have blight. These plants must be carefully sealed in plastic so as not to spread the blight spores. DO NOT COMPOST. Composting will spread the spores.
NPR reports that this outbreak was similar to that which caused the great potato famine.
For more information:
http://www.tomatocasual.com/2008/08/17/tc-flashback-tomato-blight-and-diagnoising-tomato-problems/
