Nearly 2,200 people attempted to bring loaded firearms through airport security checkpoints in the United States last year, the Transportation Security Administration announced Thursday.

The discoveries were part of a record number of firearms that TSA officials found in carry-on bags at airport checkpoints across the country, the administration said in its year-end report.

The TSA said it found an all-time high of 2,653 firearms in carry-on bags in 2015, and 2,198 of those weapons were loaded. The number of loaded firearms discovered almost equals the 2,212 loaded and unloaded firearms that TSA officers found in 2014, the former record number.

Travelers aren’t allowed to pack weapons in carry-on bags, but the TSA reports seeing a significant rise in the number of firearms it finds while screening the bags at checkpoints.

Officers found just 660 firearms in 2005, yet that has more than quadrupled in the years since. There was a 20 percent increase in the number of firearms discovered between 2014 and 2015.

TSA Administrator Peter V. Neffenger issued a statement on the discoveries, saying better training has helped officers become “more adept at intercepting these prohibited items.”

The statement didn’t address if there were any other potential factors for the increase, such as a possible rise in the number of people who were trying to fly with weapons in their carry-on bags.

Travelers can transport firearms in their checked bags, the TSA says, but the guns must be unloaded and properly packed. Travelers also must inform the airline that the luggage contains a firearm.

Still, the TSA said it’s finding the firearms in carry-ons at more airports — 236 last year, up 12 from 2014.

TSA officers at Dallas/Fort Worth International Airport found more firearms in carry-on bags than their counterparts at any other airport, the TSA said, with 153 discoveries in total. Officers at Hartsfield-Jackson Atlanta International Airport (144) and Houston George Bush Intercontinental Airport (100) each recorded 100 or more discoveries.

Denver International Airport (90), Phoenix Sky Harbor International Airport (73), Nashville International Airport (59), Seattle-Tacoma International (59), Dallas Love Field Airport (57), Austin-Bergstrom International (54) and William P. Hobby Airport (52) rounded out the top 10, the TSA reported. Five of the top 10 airports with the most firearm discoveries are located in Texas.

The discoveries came the same year amid a troubling year for the TSA.

Homeland Security Secretary Jeh Johnson removed the administration’s former acting administrator, Melvin Carraway, from his post in June after the Inspector General’s office conducted tests in which auditors tried to bring prohibited items through security checkpoints.

Inspector General John Roth testified before the House Committee on Oversight and Government Reform in November, saying the results of their most recent tests yielded “disappointing and troubling” results.

“Our testing was designed to test checkpoint operations in real world conditions. It was not designed to test specific, discrete segments of checkpoint operations, but rather the system as a whole,” Roth told the committee. “The failures included failures in the technology, failures in TSA procedures, and human error. We found layers of security simply missing.”

Johnson issued a variety of new directives after receiving the preliminary test results in an effort to boost airport security and correct some of the shortcomings the auditors identified.