Passenger shot dead in airport bomb drama

American air marshals shot and killed a passenger who claimed to be carrying a bomb in a bag, and then tried to bolt from a plane that was about to take off from Miami International airport bound for Orlando, Florida.

The incident is believed to be the first of its kind involving armed federal marshals who travel on many domestic commercial flights and on some international routes into the US.

It occurred as an American Airlines Boeing 757 that earlier arrived from Medellin, Colombia, was preparing to depart its gate, just before 2pm local time.

At the last moment, Rigoberto Alpizar, a 44-year-old Costa Rican-born US citizen, leapt from his seat and tried to leave the plane. He was instantly confronted by air marshals who ordered him to stop. He refused, and " four or five" shots were fired, according to witnesses. Mr Alpazar died shortly afterwards.

Mary Gardner, another passenger, told a Miami TV station that the man ran down the aisle from the rear of the plane. "He was frantic, his arms flailing in the air," she said. "A woman followed, shouting, 'My husband! My husband!'," Ms Gardner said.

Initial speculation was that, given the origin of the flight in a city virtually synonymous with South American cocaine production, the man might have been involved with drug trafficking.

But, as more details emerged, it seemed all but certain that the entire episode was a tragic accident. According to Ms Gardner the woman saying she was Mr Alpizar's wife said he suffered from bipolar, or manic depressive, disorder and had not taken his medication.

Another witness is said to have described the man as acting if he were " mentally unbalanced". Police later confirmed that no bomb was found, although three other bags were destroyed in controlled explosions on the runway ­ though it did not appear they contained bombs.

After a delay of less than an hour, the airport concourse had been reopened for business.

"This was an isolated incident, no one else was hurt," Dave Adams, a spokesman for the air marshals service said. "They [the marshals] did what they were trained to do."

Even so the episode will be closely scrutinised, and questions are bound to be asked whether the air marshals acted too rashly. Within hours, some experts were suggesting they should have waited before using deadly force, though the majority view was that the marshals acted correctly.

Air marshals, long employed by the Israeli airline El-Al, entered into widespread use in the US after 11 September 2001. Marshals are armed. But they are plain-clothed, indistinguishable (as they are meant to be) from ordinary passengers.

They are employees of the revamped Homeland Security Department, they are highly trained for a job that requires them to make instant judgements whether to intervene to save the lives of passengers. They are not aboard every commercial flight. But it is generally assumed that they guard virtually all flights into cities such as Washington, New York and Los Angeles, considered top targets for terrorists.

The incident comes a few days after the government announced passengers will again be allowed to carry on board small sharp objects such as nail files and scissors. The move, the first relaxation of security since 2001, is intended to speed up boarding.