A man is very lucky to be alive after the laptop in his backpack stopped a bullet hitting him as he took cover during the Florida airport shooting.

Steve Frappier was in the baggage claim area of the Fort Lauderdale-Hollywood Airport terminal when gunman Esteban Santiago opened fire on Friday, killing five and injuring eight.

He told CNN that he had rushed off the plane with his laptop sticking out of his unzipped backpack.

"I was on the ground like a tortoise with the backpack," he said. He says he felt something hit him but assumed it was luggage.

Steve Frappier's life saved by his own backpack at Fort Lauderdale airport. Photo / Facebook
Steve Frappier's life saved by his own backpack at Fort Lauderdale airport. Photo / Facebook

"It was only later when I went to the bathroom to check myself out that (I found) the bullet had entered my backpack, hit my laptop," he said. "Later when I gave my bag to the FBI for investigation, they found the bullet in the pocket of my backpack."

The bullet hit the top of the laptop that was sticking out of Frappier's bag, almost certainly saving him from a bullet entering his back.

Santiago, an Iraq war veteran, took a gun out of his luggage and opened fire in a crowded baggage claim area at Fort Lauderdale's airport, months after he showed up at an FBI office behaving erratically.

Santiago, 26, was taken into custody straight after the shooting and questioned at length, was expected to face federal charges.

Santiago, who had served in the US military, arrived in Fort Lauderdale shortly before 1pm [local time] on Friday on a connecting flight from Alaska, authorities said, when he retrieved a 9mm semi-automatic handgun from his checked luggage and began firing.

Witnesses told MSNBC television he only stopped after running out of ammunition, and surrendered to police. Mobile phone video posted on social media showed travellers kneeling and treating victims on the floor next to a carousel.

Santiago had turned up at an FBI office in Anchorage in November behaving erratically and was turned over to local police, who took him to a medical facility for a mental evaluation.

- Additional reporting AAP