The attack occurred on the Outer Banks' Ocracoke Island. The man was swimming outside the first breaker when he came upon a gray shark, some 6-7 feet in length, according to Sarah Johnson, spokeswoman for Hyde County.
The shark pulled the man under the water, and the swimmer sustained bites to his rib cage, hip, lower leg and both hands, she said. The man was conscious and talking and was flown to a hospital for treatment.
"There was a big trail of blood from the water to the sand," witness Stephen Lee told CNN.
"There's still people here and some people have gotten back in the water, and the park rangers are just now trying to vacate the area," he said. "We will likely go back in the water, but maybe not get our whole bodies in today."
According to the International Shark Attack File
at the University of Florida, the Carolinas have had at least 10 shark attacks so far in 2015 -- seven in North Carolina and three in South Carolina. Among the victims, a 13-year-old girl and a 16-year-old boy both lost an arm in attacks about 90 minutes apart at Oak Island, North Carolina, on June 14.
On average, the Carolinas experience an average of just over six shark attacks per year.
A number of factors could be contributing to the apparent rash of attacks, such as warmer water and drought conditions, said George Burgess, director of the Florida Program for Shark Research.
Drought conditions reduce the amount of freshwater making it to the sea, which creates an environment along the shore where high salt levels attract more fish and sharks, Burgess said. Warmer waters have sharks in North Carolina ahead of schedule, which is a recipe for more attacks. Burgess said that people are going to the beach in higher numbers, now that school is out for the summer.
"This is a situation that we can't ignore, as we've had a number of attacks that are serious within a short period of time," he told CNN's "Anderson Cooper 360" on Wednesday night.
"There's something going on there, there's no doubt about that. It's a perfect storm of environmental and biological variables, as well as human activity," said Burgess.