Now federal authorities are trying to locate the terrorist foot soldiers, the paper says.
According to the New York Times, intelligence pointed to two potential attacks, one in the United States and one on the Arabian Peninsula.
However, it was not clear whether the suspected operatives on the ground here were involved in the opening stages of an immediate strike, or advance planning for a future one.
Also unclear was what the possible attack would involve — including whether weapons of mass destruction might be used — and exactly where and when al Qaeda planned to strike.
The intelligence prompted CIA director George Tenet to warn Congress this week that an attack — possibly involving a radiological "dirty" bomb — was possible at the end of the Muslim pilgrimage, or hajj, which ended Thursday.
In addition to Tenet's warning, there was an advisory from FEMA that citizens should stock up on food and prepare to seal their houses against poisons. The FBI warned industries on Thursday to beware plots to sabotage key facilities.
The multiple warnings have contributed to a level of anxiety higher than at any time since Sept. 11, 2001, and a patchwork of visible security measures.
Around Washington, anti-aircraft missile batteries were deployed. U.S. Capitol police bore rifles and were told to carry gas masks at all times.
FBI personnel assigned to rapid response teams that would react to any terrorist attacks have been told to have a bag packed for three days' deployment and put on standby.
Members of Congress are also being told to have necessary supplies ready in the event of evacuation.
They were told to gather up supplies, sensitive documents, medicine and a laminated list of key phone numbers in case they have to leave quickly. Congressional staffers this week received training in how to operate "escape hoods" that protect against chemical and biological substances.
There were several scares around the country Thursday, including one at an Atlanta suburban high school where a device with a timer was found and at the Dallas-Ft. Worth airport where three concourses were evacuated after an emergency exit door was found ajar.
The Times reports federal agents arrested 32 airport workers in Florida, charging they had lied to get their security IDs. The Customs Service blocked 13 ships from entering U.S. ports because too little was known about what they carried.
But if al Qaeda has been deterred by all the increased security, they're not showing it yet, reports CBS News Correspondent Jim Stewart.
U.S. officials detected that the group took immediate notice of the escalation to Condition Orange, but said there's been no letup so far in intelligence signs indicating another attack is on the way.
Eying a jittery public, President Bush planned a speech Friday at FBI headquarters to highlight steps the federal government is taking to increase security, White House spokesman Ari Fleischer said. Mr. Bush was making the short trip down Pennsylvania Avenue primarily to talk up the new Terrorist Threat Integration Center.
First announced in Mr. Bush's State of the Union speech, the center will analyze foreign and domestic intelligence gathered from a wide array of federal agencies and report to Tenet.
The new bulletin from the FBI and the National Infrastructure Protection Center was issued to companies involved in such industries as telecommunications, energy, and banking and finance, as well as operators of water systems and electric utilities, law enforcement agencies and emergency services.
Officials believe al Qaeda could target these entities with chemical, biological or radiological attacks. Such an attack, officials say, could prompt terror and mass casualties and disrupt the regional or national economy.
Industry officials should check out their employees in an effort to root out any terrorists who may have been working there for years, waiting for the signal to strike. Al Qaeda's mode of operation is patience, sometimes taking years to plan an attack — as it did for those that occurred on Sept. 11, 2001.
Company officials should make sure that security routines are varied and think back to any unusual incidents in the past that might indicate their facility was under surveillance or being targeted.
For people who might be faced with or respond to an attack, the bulletin recommends reading the Chemical, Biological and Radiological Incident handbook available on the CIA Internet site. This handbook describes warning signs of chemical, biological and radiation attacks and steps individuals can take to protect themselves.
The FBI bulletin urges people who come in contact with a suspect substance to "cover their mouths with a cloth while leaving the area, avoid touching surfaces and wash their hands thoroughly."