U.S. citizens who are on the government's list of people banned from flying because they're considered terror threats are not prevented from learning how to fly in schools around the country, according to government regulations.

Such a person may have to drive across the country to learn how to fly a plane because he or she would likely be stopped from boarding a commercial airliner. But the security checks put in place after the 9/11 attacks will not keep the person from receiving pilot training.

The security loophole was raised during a hearing Wednesday to examine the Homeland Security Department's programs to screen foreigners who want to attend flight schools in the U.S. Some of the 9/11 hijackers were able to learn to fly in the U.S. while living in the country illegally. The government put in several more layers of security after the attacks, and foreigners now receive criminal background checks and are screened against terror watch lists before they are allowed to begin training. U.S. citizens, however, are not subject to the same scrutiny.

"I was stunned. That just caught me completely off guard, and I'm pretty angry about it," Rep. Mike Rogers, R-Ala., said after the hearing. "Everybody should be concerned."

The government has other screening requirements for someone to receive a pilot's license or other certificate to fly a plane which include criminal background checks and screening against terror watch lists. But Rogers said if the government doesn't want someone on an airplane because he or she is a terror threat, there's no reason why that person should be allowed to learn how to fly.

There are about 500 U.S. citizens on the no-fly list, according to an intelligence official speaking on condition of anonymity to discuss the sensitive numbers.

Kerwin Wilson, the Transportation Security Administration official who oversees the flight school screening program, said he did not know whether an American on the no-fly list has actually undergone flight training in the U.S. in the past 10 years.

"Keep in mind, the way the program is set up, there's layered security in place," Wilson said, adding that once someone receives a flight certificate, he or she is screened against other criminal and terrorism databases regularly. Wilson also cautioned that putting U.S. citizens through these additional security checks could cost more money.

This did not allay the concerns of lawmakers.

Rep. Bennie Thompson, D-Miss., and the top Democrat on the House Homeland Security committee, said the only thing the government does not do for a U.S. citizen on the no-fly list is give him or her a license to fly a plane.

"We've trained them to do it. That's my concern," Thompson said.

Rogers, chairman of the subcommittee that held Wednesday's hearing, said he plans to raise this with the head of the TSA, and if the agency can't fix the problem, he plans to introduce legislation that would.

The TSA said it does not have the authority to do background checks on U.S. citizens who want to train at flight schools unless the person already has a certificate from the Federal Aviation Administration.

"In compliance with its statutory authority, TSA conducts background checks for foreign flight school applicants seeking training at FAA certified flight instruction schools and vets FAA certified individuals on a continuous basis," TSA spokesman David Castelveter said.

As it is, the TSA's program to screen foreigners has its own security loopholes, according to the Government Accountability Office, a congressional watchdog agency.

The TSA screening program does not automatically determine whether a prospective flight student is in the U.S. legally, said Stephen Lord, who heads GAO's homeland security and justice programs. In 2010, law enforcement investigated a flight school in the Boston area and found that eight people at the school approved for flight training by TSA were in the country illegally, and 17 more had stayed in the country longer than they were allowed, Lord told lawmakers. The owner of the flight school was in the country illegally as well.

The TSA and Immigration and Customs Enforcement have agreed to share more information with each other, officials from those agencies said.