The officials cautioned the information, including raw intelligence, was still developing.

The officials, who spoke on condition of anonymity, said they were investigating whether one group of hijackers crossed the Canadian border at a checkpoint and eventually went to Boston's airport, where an American Airlines flight was hijacked and flown into the World Trade Center in New York.

The officials confirmed a car believed to belong to the hijackers was confiscated in Boston and contained an Arabic language flight manual.

Law enforcement officials said a hotel room in the Boston area believed to have been used by one of the hijackers was searched by the FBI Wednesday afternoon but no arrests were made. The officials said the room was vacant but included information linking it a name on the manifest of one of the hijacked flights. They declined to identify the man.

However, a Venice, Fla., man who was interviewed by the FBI said agents told him two men who stayed in his home while training at a local flight school were the hijackers. Charlie Voss said the agents identified the men as Mohamed Atta and one known as Marwan.

The FBI in Miami issued a national bulletin for law enforcement agencies to look out for two cars. Records with the Florida Division of Motor Vehicles show that one of the vehicles the FBI was pursuing - a 1989 red Pontiac - was registered to Atta.

Authorities also were developing intelligence linking the suspected attackers to a band of bin Laden sympathizers in Canada, some of Algerian origin, who are suspected of planning an unsuccessful terrorist attack in the United States during the millennium celebrations.

The officials declined to be more specific.