MIAMI, Florida (CNN) -- A federal air marshal shot and killed a 44-year-old U.S. citizen on a boarding bridge at Miami International Airport after he said he had a bomb, several sources familiar with the incident told CNN.

American Airlines Flight 924 was in Miami on a stopover during a flight from Medellin, Colombia, to Orlando, Florida, when the man, idenitified as Rigoberto Alpizar, said there was a bomb in his carry-on luggage, a Department of Homeland Security official said.

Alpizar was confronted by a team of federal air marshals, who followed him down the boarding bridge and ordered him to get on the ground, the official said.

When Alpizar appeared to reach into his baggage, at least one shot was fired, wounding the man, the official said, adding that the marshals' actions were consistent with their training. Officials said later that the man died of his injuries.

Upon investigation, there was no evidence that Alpizar had a bomb, an official said.

Alpizar had boarded the plane in Colombia, Air Marshal Service spokesman Dave Adams said. After he got off the plane in Miami and went through customs, he got back on the plane and said he had a bomb, Adams said.

Air marshals asked him to get off the plane, which he did, but when they asked him to put his bag down, he refused, Adams said. Alpizar then approached the marshals in an aggressive manner, at which point two or three shots were fired, he said.

This is the first time an air marshal has fired a weapon on or near an airplane, a federal official said.

Footage from the scene shows armed SWAT team members carrying rifles outside the aircraft, along with more than a dozen of police vehicles. Paramedics were standing on the stairway to the aircraft.

The Boeing 757, which can hold about 180 passengers, was due to take off for Orlando at 2:18 p.m. ET. It had arrived in Miami at 12:16 p.m. ET, according to the airline's Web site. No other flights at Miami International were disrupted Wednesday, an airport official said.