OCRACOKE, N.C. -- A shark bit a 68-year-old man several times Wednesday in waist-deep water in North Carolina, officials said, the seventh attack in the state's coastal waters in less than three weeks.

The man suffered wounds to his ribcage, lower leg, hip and both hands as he tried to fight off the animal, said Justin Gibbs, a local emergency official. The attack happened around noon on a beach on Ocracoke Island, he said.

"The individual was actually located right in front of the lifeguard tower when it occurred," said Gibbs, who said witnesses reported the animal was about 7 feet (2 metres) long. "He was pulled under by the shark. He was bit several times."

The victim was swimming in waist-deep water with his adult son about 30 feet (9 metres) offshore, the National Park Service said in a news release. There were no other swimmers injured.

The man is the seventh person attacked along the North Carolina coast in three weeks, the most in at least 15 years. Most were attacked in water similarly shallow. The injuries ranged from minor ones to the heel and ankle of an 8-year-old.

Shark experts say the recent spate of attacks along on the coast of the Carolinas is due to so many more people getting in the water. Americans made 2.2 billion visits to beaches in 2010, up from 2 billion in 2001, according to a U.S. Army Corps of Engineers estimate.

Scientists say that there have been reports of small bait fish coming closer to shore this summer, which attracts sharks. There have also been reports of larger numbers of sea turtles along the coast, which sharks also like to eat.

Vacationer Laura Irish Hefty said she was about 100 yards (meters) away when she saw a crowd gathering on the beach and went to investigate. She said her husband saw blood on both of the man's legs. The man was treated on the beach for about 20 minutes, according to Hefty, and then an emergency helicopter flew him to a local hospital.

Swimmers were back in the water at that spot within a couple of hours after the attack, Hefty said. "Nobody seems to be that scared," she said.