Ken Wainstein, U.S. attorney for the District of Columbia, made the disclosure Thursday during a congressional hearing in which the Bush administration pushed for renewal of provisions of the Patriot Act that make it easier for investigators to obtain library and other records.
Wainstein said the hijackers used the computers four times in August 2001, including once on Aug. 30 to check on reservations that had been made for Sept. 11.
He said the Internet accounts used were registered to hijackers Nawaf Alhamzi and Khalid Almihdhar.
Wainstein did not identify the college. But an official with William Paterson University in Wayne - the state college closest to where the hijackers lived just before the attacks - said investigators had seized several public-access computers from the library shortly after the attacks.
Judiciary Committee Chairman F. James Sensenbrenner Jr., R-WI, said the testimony highlighted the need to renew certain Patriot Act provisions.
"We put Americans' lives at risk if we foolishly provide sanctuaries - even in our public libraries - for terrorists to operate," he said.
Alhamzi and Almidhar were two of the five hijackers who seized American Airlines Flight 77 after it took off from Dulles International Airport outside Washington and crashed it into the Pentagon.
They were among as many as six Sept. 11 hijackers who lived in Paterson shortly before the attacks.
By Wayne Parry