Three loaded guns and an inert grenade were discovered at Hartsfield-Jackson International Airport security checkpoints over the Labor Day weekend, according to the Transportation Security Administration.

That brought the total number of firearms caught at the Atlanta airport for the year to date to 106. That's just three gun discoveries away from the total of 109 found in the entire year of 2014. Hartsfield-Jackson ranks No. 1 among the nation's airports for the number of guns caught in carry-on bags.

The Labor Day travel period attracted a record number of travelers, and the three loaded guns were all discovered Friday — a Smith & Wesson 9mm at 10:15 a.m., followed by a Titan .25 caliber at 11:15 a.m. It wasn’t until 7:40 p.m. that a passenger was found to have a Luger 9mm.

Then on Monday morning, a traveler with an inert grenade in a carry-on bag showed up at a checkpoint.

In such incidents, TSA alerts airport police, who take the passengers and the contraband items to the airport precinct.

Passengers can travel with guns in checked baggage if the firearms are properly packed and declared, but they are not allowed in carry-on bags. Grenades — even inert ones or replicas — are banned from carry-on and checked bags.

Although gun owners with proper licenses are not automatically arrested if caught with a gun at a checkpoint, they can still face a TSA civil penalty of up to $11,000.

“Our advice is to look through bags thoroughly before coming to the airport to make sure there are no illegal or prohibited items,” according to TSA spokesman Mark Howell.

TSA's website lists what items are prohibited in checked bags vs carry-on bags.