(NEW YORK) -- U.S. officials tell ABC News they do not have names or physical description for three terrorists allegedly plotting an a terror attack to mark the tenth anniversary of 9/11 , and that so far, there have been no matches made in the first analysis of flight records into the U.S.
No significant new information has come in to authorities Friday that adds to the threat picture, according to administration, law enforcement and intelligence officials.
Still, with the anniversary less than 48 hours away, officials say they have no choice but to act as if the threat is real and the clock is ticking.
"Al Qaeda again is seeking to harm Americans and in particular to target New York and Washington," said Secretary of State Hillary Clinton in New York Friday. "We are taking this threat seriously. Federal, state and local authorities are taking all steps to address it."
It was only two days ago, on Wednesday in Pakistan, according to officials, that the CIA developed the information about a possible al Qaeda terror plot targeting the U.S.
Three men, including at least one American citizen, had allegedly travelled to the U.S. in mid- August, from Pakistan through Dubai, assigned to attack New York or Washington with a vehicle bomb on Sept 10, 11 or 12.
Officials call the source credible, and the information very specific, but still unconfirmed.
Late Wednesday night, the intelligence was relayed to Washington and CIA headquarters.
Early Thursday, at the White House, the President and the Vice President received the first of several briefings on the threat.
Around 7 pm. Thursday, as the President arrived to address Congress, the FBI and the CIA were in high gear.
"You use all the resources that we have, people are working 24/7 on this issue," said Rep. Dutch Ruppersberger, D-Md., ranking minority member of the House Intelligence Committee, who was among the members of Congress briefed on the alleged threat. "Any time you get a reliable source and you're attempting to corroborate it or confirm it, you use all the resources that we have. People are working 24/7 on this issue."
Late last night, the FBI and Homeland Security issued a bulletin to 18,000 law enforcement agencies detailing the threat, including explosives, small arms and poisons.
At first light Friday morning, police in New York set up roadblocks and traffic checks throughout the city. Trucks passed through a cordon of officers and cars with radiation monitors and other sensors, backing up traffic for miles. Heavily armed police and national guardsmen carried out a highly publicized drill at New York's Grand Central Station.
It was the high quality of the initial information that triggered the massive rapid police response in Washington and New York, and the all hands intelligence community and law enforcement manhunt, according to one senior official who spoke with ABC News.
"What's striking about this particular information is its clarity. Usually intelligence comes in bits and pieces and officials have to connect dots. Here, I'm told, there were no dots to connect, there was so much detail in one place at one time. It was all laid out. If it's a plot it is well-planned and there's an intention to go forward with it. If it turns out not to be real then it's definitely not. There is no middle ground."
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