Not sure what that means — were the Madrid bombings, for instance, “on the scale of 9/11”? — but an awful lot of people in the know are scrambling. Combine this with that ominous Journal piece from last night and it sure sounds like someone’s worried about WMD, probably of the chemical variety given the FBI warnings to cops about foul odors and large window fans.

Hundreds of FBI agents are on the ground in Colorado, conducting round-the-clock surveillance on five suspects – including a man who recently visited Queens, sources told The News…

“The FBI is seriously spooked about these guys planning another 9/11,” a former senior counterterrorism official told the News. “This is not some … FBI informant-driven case. This is the real thing.”…

The 24-7 counterterror operation included Foreign Intelligence Surveillance Act warrants used to intercept calls and e-mails, as well as overseas-linked wiretaps to eavesdrop on Arabic and Pashto-speaking targets.

Sources said the investigation’s targets are Afghans – an unusual development. Al Qaeda prefers Arabs and Pakistanis as there [sic] overseas operatives.

The Post IDs the Colorado suspect as an Afghan known as “Najibullah” and claims that he trained with Al Qaeda. Could be that AQ wants to put an Afghan stamp on the next attack to frame it as some sort of reprisal for the U.S. occupation, but that’s just me guessing. As for how he got away, it seems we jumped too soon:

The FBI, meanwhile, is furious with the NYPD for bungled intelligence gathering that tipped off Najibullah that he was under surveillance, sources said.

Federal agents working with the Joint Terrorism Task Force asked their NYPD counterparts to discreetly gather intel on Najibullah.

Rather than slyly contact their list of sources and informants the NYPD canvassed the suspect’s old Flushing neighborhood and flashed around his picture.

Eventually the imam of the Masjid Hazrat Abu Bakr Islamic Center learned of the investigation and contacted the man’s family to let them know that he was subject of a law enforcement inquiry.

Great work, imam. You’re a true patriot. No arrests so far, no bomb materials recovered. Where do they go from here?