Najibullah Zazi, 24, and his father, Muhammad Zazi, 53, were arrested in Aurora, Colo., late Saturday and charged with "knowingly and willfully making false statements to the FBI in a matter involving international and domestic terrorism," the department said Sunday. A third man, Ahmad Wais Afzali, 37, an Afghanistan native, was arrested in New York on the same charge.
"The arrests carried out tonight are part of an ongoing and fast-paced investigation," David Kris, assistant attorney general for national security, said in a statement.
The Justice Department said the FBI is investigating "several individuals in the United States, Pakistan and elsewhere relating to a plot to detonate improvised explosive devices in the United States."
But Kris said law enforcement officials had no specific information on the timing, location or target of any planned attack.
In affidavits, agents said they legally intercepted a Sept. 11 phone conversation in which Najibullah Zazi told Afzali that his rental car had been stolen and he feared he was being "watched." Afzali allegedly asked if there was any "evidence in his car" and Zazi said no, the department said.
An FBI search of Najibullah Zazi's rental car, which had been in the New York borough of Queens, turned up a laptop computer containing an image of nine pages of handwritten notes with directions on making, handling and setting off explosives, the affidavits said.
But law enforcement officials said Zazi denied ever seeing the document or writing the notes.
During FBI questioning Thursday and Friday, the affidavits say Zazi admitted that during a 2008 trip to Pakistan, he attended courses at an al-Qaida training facility.
If convicted, each of the men would face eight years in prison.
FBI agents raided Zazi's Aurora apartment Wednesday. His trip to New York, where he allegedly stayed Sept. 9-Sept. 12, triggered a series of raids of homes in the city's Queens borough because of concerns about an alleged plot to attack the city.
Notable deaths of 2014 [PHOTOS]