Associated Press WriterWASHINGTON (AP) -- Federal authorities are investigating whether four separate cells of terrorists were involved in Tuesday's devastating attacks. At least one set of hijackers is believed to have crossed from Canada and had ties to Osama bin Laden, law enforcement officials said Wednesday.
Attorney General John Ashcroft said authorities who reviewed intelligence have "numerous credible leads."
FBI agents obtained information from Internet providers, conducted searches, and questioned people in Florida and Massachusetts. Early evidence indicated the attacks were tied to the wealthy Arab and accused terrorists, including communications among bin Laden supporters.
But officials cautioned that the information, including raw intelligence, was still developing. No significant arrests were made as of midday Wednesday.
Ashcroft said authorities were conducting interviews, reviewing airline manifests and pay phone records to identify the attackers. He said each hijacked plane was overtaken by between three and six hijackers armed with knives and box cutters.
"The department of Justice is undertaking perhaps the most massive and intensive investigation ever conducted in America," Ashcroft said.
FBI Director Robert Mueller said investigators had two goals: identify the hijackers and any accomplices both inside and outside the United States.
Mueller said individuals had been detained and questioned but there have been no arrests at this point.
The director said agents have followed leads that the hijackers or their associates had been in Florida, Boston and Providence, R.I.. He said authorities are "attempting to create the travels" of the suspected terrorists.
Officials said authorities were gathering evidence that the four terrorist cells may have had prior involvement in earlier plots against the United States, including the USS Cole bombing and the foiled attack on U.S. soil during the millennium celebrations.
FBI agents obtained information from Internet providers, conducted searches, and questioned people in Florida and Massachusetts. Early evidence indicated the attacks were tied to the wealthy Arab and accused terrorist, including communications among bin Laden supporters.
But officials cautioned the information, including raw intelligence, was still developing.
"This could have been the result of several terrorist kingpins working together. We're investigating that possibility," one law enforcement official told The Associated Press.
Added a second official: "The evidence suggests these cells each operated the same way at the same time but we don't know yet whether each knew of the other's activities."
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 made their way to Boston, 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 that the FBI on Wednesday afternoon searched two hotel rooms in the Boston area believed to have been used by the hijackers. The officials found information linked to a name on the manifest of one of the hijacked flights. They declined to identify the man.
A Venice, Fla., man said FBI agents told him that 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.
Ashcroft said authorities believe the hijackers were professionally trained pilots.
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.
The FBI has already received more than 700 tips from a special Web site seeking information on the attacks.
Agents served search warrants on major Internet service providers in order to get information about an e-mail address that may be connected to Tuesday's terrorist attacks. Among those who received warrants was Earthlink, officials said.
AOL, the nation's largest provider, said it will comply with requests quickly.
The FBI interviewed Voss, of Venice, Fla., about two men who stayed with him and his wife for a week in July 2000 while taking small-plane flight training at the municipal airport.
FBI agents "informed me that there were two individuals that were students at Huffman Aviation, my employer, and FBI told me they were involved in yesterday's tragedy," Voss said.
The couple accepted the two men as house guests as a favor to the company, Voss said. The men, who stayed just a few days, trained at the airport and came to the house to sleep, he said.
Lawmakers, including Sen. Orrin Hatch, R-Utah, believe bin Laden may have been behind the attacks. "I don't think everyone in Congress has enough information to make those assumptions," Justice Department spokeswoman Mindy Tucker said.
She said investigators are following all credible leads, but declined to comment on whether the government is close to arresting anyone. The 700 tips came from a special FBI Web site seeking information on the attacks.
From broken bits of hijacked airplanes to intelligence intercepts, the FBI is collecting evidence in its search for those responsible for the attacks. At the Pentagon, an FBI team recovered parts of the airplane's fuselage and sought the black box recorder that could provide conversations from the cockpits of the doomed planes.
"Everything is pointing in the direction of Osama bin Laden," said Hatch, the top Republican on the Senate Judiciary Committee.
A flight manifest from one of the ill-fated flights included the name of a suspected bin Laden supporter, Hatch and several law enforcement officials confirmed. And U.S. intelligence obtained communications between bin Laden supporters discussing Tuesday's attacks on the World Trade Center in New York and the Pentagon, Hatch said.