Miami ? The passenger shot to death by air marshals in Miami had been agitated before boarding the plane and was singing “Go Down Moses” as his wife tried to calm him, a fellow passenger said Thursday.

“The wife was telling him, ‘Calm down. Let other people get on the plane. It will be all right,”‘ said Alan Tirpak.

“I thought maybe he was afraid of flying,” Tirpak said.

Tirpak took his seat, and Rigoberto Alpizar, 44, and his wife eventually boarded the plane. Then, Alpizar bolted up the aisle and onto the jetway, where two air marshals confronted him.

“He was belligerent. He threatened that he had a bomb in his backpack,” said Brian Doyle, spokesman for the U.S. Homeland Security Department. “The officers clearly identified themselves and yelled at him to ‘get down, get down.’ Instead, he made a move toward the backpack.”

Agents are trained to shoot to stop a threat, and the situation on the jetway at Miami International Airport Wednesday appeared to pose one, said John Amat, a deputy with the U.S. Marshals Service in Miami.