The NY Post reports: The terror plot unearthed after raids on three Queens homes involved operatives detonating nine explosives-laden backpacks to kill “as many people as possible,” The Post has learned.

“They were going to blow up several places simultaneously and take out as many people as possible — a large number of people,” a federal law-enforcement official said.

Empty backpacks were among the evidence seized from one of the Flushing apartments raided by the FBI. Authorities also removed computers, cellphones and other material. No explosives were found.

The predawn raids were sparked by the reappearance in New York City of an al Qaeda associate who’d gotten top-level training in bomb-making at a Pakistani terrorist camp, sources said.

Najibullah Zazi was schooled in demolitions and military tactics along with several other men; all eventually settled in Queens, according to the sources.

But when Zazi got wind that he was being watched, he hightailed it back to Aurora, Colo., where he now lives, although he was shadowed on the plane by FBI agents.

Now, feds are virtually monitoring Zazi’s every move, phone call and computer stroke, the sources said.

Law enforcement also is trying to track down former confederates-in-arms whom he may have met over the past week, the sources said.

Last week, he drove from Colorado to Queens in a rental car. He told The Associated Press he was pulled over during a “traffic stop” while driving into the city.

Even as the investigation intensifies, the FBI is furious with the NYPD for tipping off Zazi — by canvassing his old Flushing neighborhood rather than discreetly inquiring about him.

Sources said the feds would have preferred to lie in wait a little longer to see what he and his contacts were planning.

An NYPD spokesman called those claims “an utter fabrication.”