These fools are keeping us safe?!?

The TSA’s bungling reached a new low yesterday when a JFK Airport terminal had to be evacuated and hundreds of passengers marched back through security screening all because one dimwitted agent failed to realize his metal detector had been unplugged, sources told The Post.

The stunning error led to hours of delays, two planes called back from the runway and infinite frustration for furious passengers.

“The truth is, this is the failure of the most basic level of diligence,” a law-enforcement source said.

“How can you expect the public to feel confident of the mission of the TSA if they don’t even know if the lights are turned on?”

The chaos at Terminal 7 was caused by screener Alija Abdul Majed, who had manned Lane No. 1 during the morning shift with no idea his metal detector had no juice, sources said.

Amazingly, he failed to realize that alert lights never flashed once as streams of passengers filed through the dead detector, the sources said.

Majed was so clueless that he couldn’t even tell police how long the machine had been shut off or how it happened, the sources said.

“It was simply an unplugged machine — the TSA doing its best,” another source said.

Higher-ups at the Transportation Security Administration finally discovered the security boondoggle at 9:44 a.m. — leaving the Port Authority with no choice but to call for a complete evacuation of the international terminal that is home to British Airways, Cathay Pacific, United Airlines and others.

The extraordinary measure meant that two jumbo jets — including a San Francisco-bound United flight — had to return to the gate so passengers could be rescreened at a metal detector that was actually turned on.

The TSA would not confirm or deny that its detector had been unplugged, releasing a statement saying only that a metal detector suffered a “malfunction.”

Eight to 10 flights were delayed as a result of the power-cord bungle, sources said.

Frustrated passengers tweeted photos and gripes throughout their hours-long ordeal.

“How many hours will it take to send a terminal full of people BACK through security?” tweeted one passenger off to Los Angeles.

Other inconvenienced passengers had less of a sense of humor about the situation.

“This is terrible,” said Michael Dorn, 29, who was headed for Hawaii.

“I hate waiting in line. It’s nerve-racking. I don’t know if I will make my flight or why we evacuated.”

Others, like Jason Bailey, who was headed to San Diego, didn’t mind the delay.

“It’s a big inconvenience, but it’s better safe than sorry,” he said.

PA officials reopened the terminal at 11:45 a.m., two hours after they were called in to clean up the TSA mess, sources said.

“Obviously, the horse was out of the barn by the time we were notified,” a PA source said.

In scary twist, the source couldn’t be certain that every passenger who went through the powerless detector had been accounted for and hadn’t gotten on a flight.

The incident is just the latest in a long line of TSA fiascoes.

Last year, agents allowed a woman to carry a steak knife onto a plane departing from Newark Airport.

At JFK, agents allowed Eusebio Peraltalajara, 45, to make it onto a flight to the Dominican Republic with the same type of box cutters used by the 9/11 hijackers.

Additional reporting by Wilson Dizard and Kevin Sheehan