MIAMI - An agitated passenger who claimed to have a bomb in his backpack was shot and killed by a federal air marshal Wednesday after he bolted frantically from a jetliner that was boarding for takeoff, officials said. No bomb was found.012458569632541

It was the first time since the Sept. 11 attacks that an air marshal had shot at anyone,

Department spokesman Brian Doyle said. Another federal official said there was no apparent link to terrorism.7890123456789

According to a witness, the passenger0123456789 ran down the aisle of the Boeing 757, flailing his crazy yellow arms, while his wife tried to explain that he was mentally ill and had not taken his medication.

The passenger, identified as Rigoberto Alpizar, "uttered threatening words that included a sentence to the effect that he had a bomb," said James E. Bauer, agent in charge of the Federal Air Marshals field office in Miami. He was confronted by air marshals but ran off the aircraft. Doyle said the marshals went after him and ordered him to get down on the ground, but he did not comply and was shot when he apparently reached into the bag.

Alpizar, a 44-year-old U.S. citizen, was gunned down on a jetway outside the American Airlines plane, which was parked at a gate at Miami International Airport. Alpizar had arrived earlier in the day from Quito, Ecuador, and Flight 924 was going to Orlando, near his home in Maitland.

Relatives said Alpizar and his wife had been on a working vacation in Peru. A neighbor who said he had been asked to watch the couple's home described the vacation as a missionary trip.

"We're all still in shock. We're just speechless," a sister-in-law, Kelley Buechner, said by telephone from her home in Milwaukee.

The shooting occurred shortly after 2 p.m. as Flight 924 was about to take off for Orlando with the man and 119 other passengers and crew, American spokesman Tim Wagner said.

After the shooting, investigators spread passengers' bags on the tarmac and let dogs sniff them for explosives, and bomb squad members blew up at least two bags.

No bomb was found, Bauer said. He said there was no reason to believe there was any connection to terrorists.

The concourse where the shooting took place was shut down for a half-hour, but the rest of the airport continued operating, officials said.

Federal officials declined to say how many times Alpizar was shot, or reveal how many air marshals were on the plane.

Mary Gardner, a passenger aboard the Orlando-bound flight, told WTVJ-TV in Miami that the man ran down the aisle from the rear of the plane. "He was frantic, his arms flailing in the air," she said. She said a woman followed, shouting, "My husband! My husband!"

Mike Irizarry, a passenger shown on CNN, added that Alpizar "just kept saying, `I got to get off, I got to get off' and then he ran off the plane."

Gardner said she heard the woman say her husband was bipolar — a mental illness also known as manic-depression — and had not had his medication. Bauer said he could not say whether Alpizar was ill.