(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.

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.