Authorities say Craig Adam Hutto, 16, of Lebanon, Tenn., was off Cape San Blas while fishing in waist-deep water about 60 feet from shore. The shark tore into Hutto's right thigh.
A doctor who happened to be nearby began treatment before the boy was taken to the hospital, police say.
Hutto was airlifted to Bay Medical Center in Panama City, Fla., where Doctors Glen Summers and Reid Finney were part of the team that operated on him.
"It was obvious from walking into the room that the leg was not salvageable and that our job was to save his life, not save his limb," Finney said, so it was really a matter of saving Hutto's life.
Summers said, "Obviously, (Hutto) had suffered a terrible injury, was in shock, had lost a lot of blood." He called the blood loss "massive."
The prompt medical attention Hutto got on the beach was a "critical factor" in saving his life, Summers told Smith.
Summers adds that he'd never seen injuries so devastating from an environmental event, as opposed to a motorcycle or automobile crash.
But, he says, Hutto's long-term prognosis is excellent. "We obviously have a lot of things to accomplish between now and being able to say that. But he's young and otherwise healthy, so I think he should do well long term."
Hutto, whose leg was amputated in the surgery, was hospitalized in stable condition at the time of the interview.