A US Airways pilot accidentally discharged his gun in the cockpit during a flight from Denver to Charlotte, N.C., according to the Transportation Safety Administration.
The round was discharged by the pilot in the left seat and did not result in depressurization, according to government aviation sources.
The Airbus A319 landed safely after the incident Saturday and without any injuries to the 124 passengers on board, a spokesperson for the TSA told ABCNEWS.com today.
The TSA said the passengers were unaware that a gun had been fired in the cockpit.
The pilot, who both the TSA and US Airways declined to identify, was a member of the Federal Flight Deck Officer program, an initiative put in place after the Sept. 11, 2001, terrorist attacks. The initiative allows authorized members of cockpit crews to carry weapons on board.
"There are thousands of federal flight deck officers and this has never happened before," said the spokesperson. "This was probably a bit of a fluke."
The Federal Flight Deck Officer program provides training to eligible crew members on the use of firearms, use of force, legal issues, defensive tactics, the psychology of survival and program standard operating procedures, according to TSA's Web site.
Flight deck officers must requalify for the program twice a year; the pilot involved in Saturday's incident requalified in November 2007.
The gun went off in the plane's cockpit but spokespeople for both US Airways and TSA declined to comment on the position of the weapon when it was discharged, citing an ongoing investigation. The TSA also declined to say what the bullet struck.
"Federal flight deck officers are authorized and trained to carry their firearms on their person inside the flight deck of an aircraft," said the TSA spokesperson.
The weapon used by the officers are H&K 40-caliber semiautomatics.
As for the pilot's future employment with US Airways, the spokesperson for the airline told ABCNEWS.com that it's against company policy to divulge any information about the employee.
The US Airways aircraft has been grounded since the incident, pending the investigation.
ABC News' Matt Hosford contributed to this report.