Tracking unseen enemy

September 12, 2001 Posted: 1:11 p.m. EDT (1711 GMT)

As the sun rises over Manhattan's skyline on Wednesday, smoke drifts where the World Trade Center towers once stood.

(CNN) -- A day after catastrophic strikes on two renowned symbols of American power, FBI investigators moved quickly on several fronts as they searched for clues to those responsible.

Meanwhile, the search for survivors continued in the rubble at New York's World Trade Center and the Pentagon in Washington, D.C.

Latest developments

*  Law enforcement officials in Boston and Vero Beach, Florida, took several people into custody, sources told CNN. Heavily armed tactical police entered the Westin Hotel in Boston and went to the upper floors of the hotel on an operation believed connected to Tuesday's terrorist attacks. At least four ambulances were on the scene.

* The owners of a flight school in Venice, Florida, say that the FBI is investigating whether two former students were involved in the attacks.

* A car is seized in Daytona Beach, Florida, with information relating to Osama bin Laden.

CNN.COM SPECIAL REPORT  VIDEO/AUDIO Exclusive video of crash at WTC Sights and sounds  MORE STORIES Terror attacks hit U.S. Blast rocks Pentagon Industry, media figures among crash fatalities World shock over U.S. attacks  EXTRA INFORMATION Chronology of terror Partial list of those killed in Tuesday's attacks Photo Gallery CNNFN: Special Report  RESOURCES Text of Bush's address Quotes from witnesses and leaders Emergency contact information Message Board

* New York Mayor Rudy Giuliani says that "the best estimate" for the number of dead could approach "a few thousand people ... in each building."

* The nation's airports remained closed past noon today because the FAA wanted more time to put stringent security measures in place.

* President Bush asks Congress for emergency funding to aid rescue and relief efforts and calls attacks "acts of war."

* NATO is meeting to discuss invoking Article Five of its charter which would give a green light to the United States to retaliate once it determines who is responsible for Tuesday's attack and expediate assistance from other NATO members. (Full story)

* Intelligence sources tell CNN that at least two phone calls were intercepted between members of an organization connected with suspected terrorist Osama bin Laden. Phone calls mentioned that two targets had been hit. (Full story)

* The aircraft carrier USS George Washington has moved into New York Harbor

* New York rescuers are searching for two other people who have been in contact with authorities; two other police officers were rescued Tuesday night. (Full story)

* As many as 300 firefighters and police officers are missing and feared dead. (Full story)

* New York Fire Chief Pete Ganci and First Deputy Commissioner of the Fire Department William Feehan have perished.

* Boston Herald reports that authorities seized a car at Logan Airport in Boston containing "suspicious materials," including Arabic language flight manuals. FBI spokeswoman would not confirm or deny that report.

* Boston's Logan International Airport announces tightening of security. Among them: the airport will discontinue curbside baggage check-in and remove vehicles standing within 300 feet of front entrance

* Although airlines were making tentative plans to begin resuming curtailed schedules, the unprecedented grounding of all flights in the United States remained in effect until at least noon Wednesday. (Full story)

* Pentagon announces: Military jets will be seen in skies over New York and Washington for the next several days.

* Reports of three suspicious aircraft over Canada were checked out by Canadian authorities and found to be untrue, according to U.S. officials. Concern about the matter was prompted by a Canadian pilot who reported -- erroneously as it turned out -- that he was being followed by three other aircraft.

* New York City is closed to the public south of 14th Street.