(CBS) – The TSA is warning about an alarming rise in the number of guns being confiscated at airports, and part of the problem is at Chicago’s Midway Airport.

Last year, security screeners confiscated six firearms from gun-toting Midway passengers. This year, they’ve already hauled in seven handguns, with nearly two-thirds of the year still to go.

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Federal authorities want all gun owners to review the rules and follow them.

“Probably the most common excuse is, ‘I didn’t know it was there,’” Kevin McCarthy of the Transportation Security Administration says.

At Midway and across the nation more passengers are trying to board airplanes with firearms at their side.

In 2005, 660 guns were confiscated nationwide. Last year, the number rose to 2,212 – nearly a four-fold increase.

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“I think there’s a personal responsibility for any gun owner, that they ought be aware of the rules, where they can and can’t take it,” McCarthy says.

They cannot stow a gun in carry-on luggage, where the TSA usually finds them. At Midway, in January, a .38-caliber revolver was recovered with three bullets. In February, a .40-caliber Smith @ Wesson, and a .9-millimeter automatic were seized. Four more handguns were picked up in April — all with ammo, three of them loaded.

The right way to travel with guns on airplanes is to pack the unloaded gun in a hard-sided lockable case; it must be in luggage that will checked. Any ammunition must be in a separate container.

At the counter, you must declare there’s a weapon in your bag, and you must fill out at form to certify it’s unloaded.

In case you’re wondering about the numbers at O’Hare International Airport. There were 20 guns confiscated last year; only eight so far have turned up this year.

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If you’re caught with a gun, you’ll face fines from the TSA and possible felony prosecution by the state’s attorney’s office.