U.S. airports have been breaking records for the number of passengers in the past few years.

Meanwhile, the Transportation Security Administration has been breaking records for the number of guns that security officers find on passengers and in their carry-on luggage.

Last year, TSA agents seized 3,391 guns, or an average of nine a day, nation’s airports, a 28 percent increase from 2015.

Now, the TSA has set a new record. On Feb. 23, agents at various airports found 21 guns in a single day, breaking the previous one-day high of 18 firearms found on June 4, 2014.

A breakdown of the weapons and the airports where they were found shows no obvious pattern. The guns were found in small airports, including Asheville, N.C., and at big hubs, including Washington Dulles International Airport.

Nine of the firearms were 9-mm handguns, and all but one were loaded, according to the TSA. When such weapons are found, TSA agents turn the firearm and the passenger over to local police.

TSA officials won’t speculate about whether the record-setting pace of firearm seizures is the result of more passengers traveling by air, improved screening methods or both.

Agency officials note that the TSA has begun an effort to educate travelers about the laws that forbid fliers from bringing any weapons — or replica weapons — into an airplane cabin.

“I think we have a pretty robust campaign as it is, with a very popular Instagram account, regular releases about gun finds and events across the country,” TSA spokesman Nico Melendez said. “With the rules readily available on our website, app and in newspapers, we’ve done and continue to do what we can to educate.”