After two months of repeated warnings that other terrorist attacks in the US could be imminent, Bush administration officials sought yesterday to treat the crash of the Flight 587 as tragic but not necessarily sinister.
In a city shaken by the September 11th attacks and still cleaning up from the potent strain of anthrax mailed to the Senate majority leader, there was plenty of reason to believe the worst.
Immediately following the attack, Mr Tom Ridge, the White House director of homeland security who is charged with leading the US response to new terror attacks, set up a conference call involving the top law enforcement, defence and transport agencies.
But Mr Ari Fleischer, President Bush's spokesman, said in a mid-day briefing that there had been no credible threats of an attack linked to yesterday's crash.
In addition, he said that there were "no unusual communications" between pilots in the cockpit and ground controllers before contact was lost with the aircraft.
Unlike the September 11th attacks, which led to an unprecedented shutdown of the nation's entire air system, federal authorities responded yesterday only by closing four New York area airports.
White House and FAA officials said they had not ruled out any possibilities, including an on-board explosion.
But Mr Fleischer said that government officials had no information on whether an explosion had occurred.