A 24-year-old Colorado airport shuttle driver and his father were arrested on formal charges of making false statements to federal agents in an ongoing terror investigation. A third man was arrested in New York City on the same charges, the Justice Department said Sunday.

Najibullah Zazi and his father, Mohammed Wali Zazi, 53, were arrested by federal agents late Saturday at their suburban Denver homes. Ahmad Wais Afzali, 37, of Flushing, New York, also was arrested, the Justice Department said.

Authorities say Afzali and the 24-year-old Zazi are legal permanent residents from Afghanistan, and the elder Zazi is a naturalized U.S. citizen from Afghanistan.

Each was charged with knowingly and willfully making false statements to the FBI "in a matter involving international and domestic terrorism," the department said in a statement. It emphasized authorities don't know the timing or location of any planned attack.

The FBI is investigating several individuals in the United States, Pakistan and elsewhere in an alleged plot to detonate explosive devices in the United States, the Justice Department said.

In supporting documents filed with the court, federal investigators say a Sept. 11 search of Zazi's rental car in New York turned up a laptop computer that contained an image of nine pages of handwritten notes. Those notes included formulas and instructions about how to build explosives, detonators and other components of a fusing circuit, according to the affidavits.