U.S. Homeland Security officials have prepared a report listing 12 ways terrorists might attack the country and estimates of the death toll each attack might produce.
Existence of the unreleased document was first reported by the New York Times newspaper late Tuesday.
The Times says the scenarios include terrorists blowing up a chlorine tank, killing more than 17,000 people, and spreading pneumonic plague in public areas, killing 2500.
In another scenario, terrorists would infect cattle with foot-and-mouth disease at several sites, resulting in financial losses in the hundreds of millions of dollars.
Homeland Security officials say the report was drawn up to help federal, state, and local officials develop preparedness plans. The officials say there is no credible evidence that the attacks mentioned in the report are being planned.
Some information for this report provided by AP.