LOS ANGELES (REUTERS) - Two teenagers enjoying a day at the beach were badly mauled in separate shark attacks less than two hours apart on Sunday in coastal waters off Oak Island, North Carolina, casting a pall over the start of the tiny resort town's summer tourist season.

A girl about 14 years old was attacked shortly after 4pm local time, suffering grave wounds to her left arm and leg before a man swimming nearby heard her screams and came to her aid, Mayor Betty Wallace told Reuters.

Wallace said the girl, who was flown by helicopter to a hospital in Wilmington, ended up losing part of her arm, and may lose her leg as well.

About 90 minutes later, farther east along the same stretch of beach, a 16-year-old boy was bitten by a shark as authorities were still responding to the first incident, she said. That attack ended up costing the boy his left arm, according to the mayor.

Wallace said she had no details about the circumstances of either attack, including what the victims were doing in the water or how far from shore they were.

The attacks led sheriff's deputies to send special patrols up and down the shore warning beachgoers to get out of the water, and a helicopter was launched to search for a shark.

Wallace said town officials would meet on Monday morning to decide whether to officially close the beach to the public.

The beach at Oak Island, a town of about 7,000 year-round residents, was crowded on Sunday, and "the weather was beautiful," the mayor said. The twin attacks came two weeks before the July 4th holiday weekend, when Oak Island's population typically swells with 30,000 to 40,000 visitors.

Wallace said shark encounters are virtually unheard of there, adding that a long-time resident could not recall a single one in 36 years.

"I don't want everybody to think this is one of those areas where you really have to worry about shark bites," Wallace said. "But for the foreseeable future, people have to be extra vigilant."