ederal authorities have flown four people to New York City for questioning in connection with last Tuesday's terrorist attacks, including a man who was arrested in Minnesota in August after he attempted to obtain training on a flight simulator for large jetliners, officials said yesterday.

As their investigation spread to cities across the United States and overseas, authorities yesterday placed particular emphasis on Zacarias Moussauoi, who raised suspicions at a flight training facility near Minneapolis and was arrested on Aug. 17 on a passport violation.

In addition to Mr. Moussauoi, law- enforcement officials in New York were questioning two men who were pulled off a train in Fort Worth Wednesday with box cutters in their possession. The fourth person, who has not been identified, was also brought in from Texas, officials said.

One of the men seized on the Amtrak train has already been arrested in New York City under a material witness warrant, which can be used only to detain people who are believed to have significant information about criminal acts, investigators said. His apartment in Jersey City, N.J., was searched Friday and a box of evidence was removed.

The investigators provided these details as the worldwide hunt for people involved in the suicide jetliner attacks on the World Trade Center and Pentagon picked up speed, with law-enforcement officers fanning out across the country to chase suspects and sift through tens of thousands of leads.

Arrests were also made overseas. Canadian government today handed over to the United States one of two men that have been questioned in Toronto about possible links to the attacks. The Royal Canadian Mounted Police said on Saturday that the man detained this week was carrying photographs that American officials wanted to see.

The F.B.I. and local authorities in several states have detained at least 25 people, including some during house and apartment searches.

Many of those are being held simply for expired visas and other immigration problems. And it is not clear how much progress the investigators have made toward determining whether the 19 hijackers were supported by large cells of confederates or whether other potential hijackers were involved in the plots and remain at large.

The most significant figure brought to New York for questioning appears to be Mr. Moussauoi, apparently entered the United States earlier this year on a student visa sponsored by Airman Flight School in Norman, Okla. Dale Davis, director of operations at the flight school, said the company is authorized to sponsor such foreign students once they have been cleared by their respective embassies.

He said Mr. Moussaoui contacted the school in September 2000 from London, got approval from the French embassy in England, then arrived in Oklahoma and enrolled in the school on Feb. 26.

Mr. Davis said Mr. Moussaoui struggled with training and never earned a pilot's license.

Mr. Moussaoui's whereabouts over the next few months are unknown, but at some point he applied for training at Pan Am International Flight Academy , which operates a flight training facility in Eagan, Minn.

Todd Huvard, a spokesman for Pan Am, declined to comment.

Mr. Davis said he had not spoken with officials at Pan Am International about what prompted the arrest but he said any flight training facility would become suspicious of someone with such limited experience insisting that he wanted to train on a simulator for jet airliner pilots.

The two men arrested on the Amtrak train, Ayub Ali Khan and Mohammed Jaweed Azmath, had boarded a flight Tuesday morning leaving Newark International Airport for San Antonio. After air-traffic controllers ordered all flights to land after the crashes into the World Trade Center and the Pentagon, their plane diverted to St. Louis, where they got on the Amtrak train for Texas with the box cutters and thousands of dollars in cash.

Law-enforcement authorities said their movements ・and the fact that they carried box cutters similar to those used in at least some of the four hijackings ・raised suspicions that they could have been part of another potential hijacking team or been assisting the hijackers. But the authorities stressed that they had no proof that either of the men were involved in any crime.

The identity of the fourth man who was brought to New York, also from Texas, was not immediately clear.

Authorities in New York also are known to be holding a fifth man. They have refused to identify him, but they have said that he has had some ties to both Mr. bin Laden and Mr. bin Laden's brother. The man was detained at John F. Kennedy International Airport last Thursday, and he was arrested under a material witness warrant on Friday.

Just how the hijackers pulled off the attacks still remains a puzzle, though officials said the pieces being gathered continue to build a picture of 19 men, scattered throughout the country, who kept in close communication as they moved in pairs or groups toward those devastating Sept. 11 flights.

But the F.B.I. also has sent a list of more than 100 possible witnesses to more than 18,000 local and state law- enforcement agencies.

"This is all were thinking about," said officer Brian Wolfe of the Dublin, Ohio, police department, who at the F.B.I.'s request scoured area parking lots to search for two cars from New York.

NEW JERSEY

Neighbors and residents said Mr. Khan, Mr. Azmath and a third man lived quietly in a second-floor apartment in Jersey City, N.J., at 6 Tonnele Ave. They said the three were of Pakistani or Indian origin. A fourth man, they said, who was the only one in the group who spoke Arabic, lived in the apartment until three or four months ago.

"I understood that he worked in the Saudi consulate in New York," said Sussana Alou, 30, who lives next door.

Rifle-toting federal agents raided the apartment building at 10:30 on Saturday morning. Neighbors said the men worshiped at the Al Salaam mosque, less than two blocks away on 2824 Kennedy Blvd., which also served as a gathering spot for the terrorists involved in the 1993 bombing of the World Trade Center. Omar Abdel-Rahman, the blind Egyptian cleric who was the convicted ringleader of the 1993 attack, frequently preached there. Worshipers at the mosque said they did not know the suspects.

The agents, who searched several of the apartments, took at least three men away in handcuffs. Mrs. Alou, whose husband Abdel Salam, 37, was detained during the raid on Saturday, said he is being held by the Immigration and Naturalization Service because of an expired visa. She said the other men had lived in the apartment for the nine months.

In Passaic, neighbors of the three men who were arrested outside Newark Airport late Thursday said that they had largely kept to themselves but were often seen chatting on cellular phones and smoking a water pipe in the hallway.

Two of the men, Mohammad Raqqad and Ahmad Kilfat, lived on the middle floor of a three-story, three- family brown house on Tulip Lane, in an immigrant neighborhood of Hispanics where their expensive clothes and visitors' new cars seemed out of place.

A green Ford Taurus with Florida license plates that is registered to Mr. Raqqad remained across the street Friday. Nezar F. Qablawi, owner of the used car dealership in Cocoa, Fla., where the car was once sold, said that four F.B.I. agents appeared in his offices before noon on Wednesday, barely 24 hours after the attack. "They told me somebody called in and put a complaint that you guys are part of Hezbollah," Mr. Qablawi said. The assertion, he said, was absurd. Chris Hedges

FLORIDA

Federal agents continued their work today in Florida with the search of an apartment at the Delray Racquet Club in Delray Beach that has been connected to two suspects.

Agents arrived at 755 Dotterel Road late this afternoon and entered the third-floor apartment that has been linked through records to Saeed Alghamdi and Ahmed Alnami, both of whom the F.B.I. has placed aboard United Airlines Flight 93, the plane that crashed in rural Pennsylvania.

Neighbors said that two Middle Eastern men moved into the unit about four months ago and may have moved out as recently as last Sunday, two days before the attacks. The neighbors said the two men seemed inseparable and that they sometimes were visited by an older man with a salt-and-pepper beard. Two neighbors also said they often heard odd noises coming from the apartment late at night, with one woman describing it as the sound of chipping tiles and another as rolling marbles.

As many as 15 of the 19 suspected hijackers may have lived and trained in Florida. One federal law enforcement official said today that every other F.B.I. investigation in south Florida has essentially been suspended while the agents concentrate on the hijackings.
Kevin Sack

OKLAHOMA

It is not unusual for foreign students like Mr. Moussauoi to call the Airman Flight School in hopes of becoming pilots. Among such students who considered the school in July 2000 were Mohammed Atta and Marwan al-Shehhi, two of the hijacking suspects on the jetliners that crashed into the World Trade Center.

Federal agents have already questioned officials at a flight school in Tulsa, Spartan Aeronautics, about a one of the suspected hijackers, Fayed Ahmed, whose name has also been rendered as Ahmed S. Faiez. Mr. Ahmed listed the school's address on his pilot's license. School officials say they have no record of anyone with that name attending.

Another suspected hijacker, Mohammed Ahmed Al-Ghamdi, also sometimes listed as Ahmed A. al- Ghamdi, listed a Tulsa apartment complex as his address on his commercial pilots license.

In July 2000, Mr. Atta and Mr. al- Shehhi spent a night in the dormitory for Airman Flight School. Mr. Davis, the schools director of operations, said neither man had a pilot's license and that they spent a day touring the facility and inspecting the airplanes. Mr. Davis said the pair ultimately decided to go elsewhere, and records show that later in the month they began taking classes in Venice, Fla.

Jim Yardley

SAN ANTONIO

In San Antonio, federal agents searched the office of a 34-year old radiologist, according to Dr. Gerald D. Dodd, chairman of the radiology department at the University of Texas Health Sciences Center at San Antonio. The radiologist, identified in local media reports as Albader Alhazmi, is from Saudi Arabia and has been enrolled in the Health Sciences Center's diagnostic radiology residency program for nearly five years, Dr. Dodd said.

Meanwhile, investigators were contacting flight schools in San Antonio, where at least one of the hijackers, Salem Al Hamzi, appears to have maintained an address. Over the weekend, agents conducted interviews at the Boerne Stage Airfield outside of San Antonio.

Robert Bruce, the airport manager, said that the agents asked if two individuals had taken flight training there. But, Mr. Bruce said, neither he nor his staff recognized the names.

Alpha Tango Flying Service, a flight school that was formerly at the airfield frequently trained foreign pilots, Mr. Bruce said. The president of that school, Hameed Afzal, said that one former student had the same last name as one of the hijackers who have been identified by the Government. But Mr. Afzal said he has shared that information with the authorities, and been told that the full names do not match.
Kurt Eichenwald

SAN DIEGO

At least two of the men accused of hijacking the plane that crashed into the Pentagon, Khalid al-Mihdhar and Nawaf al-Hamzi, lived at some point in San Diego, but it appears that they may have left the area by the beginning of this year, an official said.

Mr. Alahazmi and Mr. Al-Midhar rented a room in suburban San Diego from a retired professor, Abdussattar Shaikh. The official said Mr. Shaikh was not a suspect in the case. James Sterngold

ARIZONA

The authorities believe that Hani Hanjoor, one of the alleged hijackers, lived in the Phoenix area off and on since as early as 1991, and was training to be a pilot. In fall 1996, and in December 1997, Mr. Hanjoor attended the CRM Airline Training Center in Scottsdale. But he was not diligent, and he did not receive a private pilot's certificate, said Paul V. Blair, the center's controller.

Mr. Hanjoor appears to have led a mostly solitary and quiet life.

Prior to his stint in Phoenix, Mr. Hanjoor apparently lived in Tucson.

The Los Angeles Times, has reported that Mr. Shaikh said that Mr. al-Hamzi called him in January and said he was in Arizona.
David W. Chen