The arrests of five men accused of flying loaded guns into New York City have revealed a gaping hole in the nation's airport security that is breathtaking in its utter simplicity and catastrophic potential. It must be plugged.

The massacre of 12 journalists and police by heavily armed terrorists in Paris Wednesday underscores the urgency of staying a step ahead of bloodthirsty extremists.

Officials allege that the key player in the gunrunning scheme was a baggage handler at Atlanta's Hartsfield-Jackson International Airport. He allegedly was able to simply walk into the secure area of the airport with guns in a backpack and hand them off to an accomplice, a passenger who had cleared security and was waiting to board a flight. Detectives bought 153 guns they say were carried to New York City on 17 flights in 2014 alone.

Airport employees who work in or have access to areas behind security checkpoints, like those who load bags or clean planes, often are not physically screened when they report to work. Pilots and flight crews are required to pass through metal detectors. Airport employees should be, too, unless officials come up with a more effective plan.

The suspected gunrunners busted last month were apparently just garden-variety bad guys, perhaps looking to avoid the long drive North or to beat rivals by providing same-day delivery on selected firearms. But the ease with which terrorists could use the same approach to smuggle guns or bombs onto planes is frightening and intolerable.

Individual airports, in conjunction with the Transportation Security Administration, develop their security plans to fit their layout, number of entrances and other unique features. The TSA requires that job applicants pass background checks. And once people are on the job, the TSA runs periodic security checks -- for instance, to ensure a worker hasn't been added to terrorist watch lists.

But very few airports use metal detectors to screen all workers daily, said Sen. Charles Schumer (D-N.Y.). Together with Brooklyn District Attorney Kenneth Thompson, he has asked the TSA to mandate that screenings be included in security plans at airports nationwide.

It's a simple fix for a lapse in security that could be deadly.