Two suspected al Qaeda terrorists who were arrested last week by federal officials were planning to poison the country's water supplies.
One of the suspects, James Ujaama, 36, was arrested last week in Denver.
Sources told Fox News that agents found documents about water poisoning - as well as other terrorism-related evidence - in his Denver apartment.
The other suspect, Semi Osman, also had instructions about poisoning water on him when he was arrested, the report said.
The government believes that Ujaama - whose brother, Mustafa, is the founder of a now-closed mosque in Seattle that is under scrutiny for links to al Qaeda - acted as a courier, delivering laptop computers to the Taliban.
Fox News also reported that investigators believe that members of the mosque were trying to establish a terrorist-training camp in Oregon and that Mustafa Ujaama visited the state, scouting a suitable location.
Sources told the network that the Ujaama brothers and Osman are tied to a radical, London-based cleric named Sheik Abu Hamza al-Masri, a one-eyed mullah who is wanted in Yemen on terrorism charges.