The FBI charged a US Airways employee with helping his roommate get a concealed, semiautomatic handgun onto a plane departing Philadelphia early Thursday.

Customer service agent Roshid Milledge switched black carry-on bags with passenger Damien Young at the gate so Young could board the 7 am flight to Phoenix with the unloaded 9 mm weapon, the FBI said in an affidavit.

Young, 29, was moving to Phoenix and had asked Milledge about the procedures for transporting guns. Milledge, 38, instead agreed to carry the bag through an employee entrance so it would not be screened by security.

An alert fellow passenger saw the switch and, sensing that Milledge seemed "fidgety," raised concerns. Young, already on the plane, allegedly denied to a US Airways manager that he had switched bags with anyone. The plane then started to taxi, but was soon called back to the gate so Young could be removed.

He then admitted the bag was his and both men gave statements, the FBI said. Milledge told agents he had grabbed the wrong laptop bag from their Philadelphia home that morning and was switching it back.

The gun is registered to Young, and he had a valid permit to carry it, authorities said.

The men were in federal custody late Thursday with court appearances expected in the next few days. Neither had a listed telephone number, and they did not appear to be represented by counsel.

The Transportation Security Administration declined comment because of the FBI investigation, spokeswoman Ann Davis said.

US Airways Flight 1195 departed Philadelphia several hours later. In a statement, the Tempe, Ariz.-based airline said only that additional passenger screening took place "after a concern was raised about a carry-on bag."

"We are cooperating with investigators fully and take security considerations very seriously," said the statement issued by spokesman Morgan Durrant.

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