Was a great white shark to blame for Cape Cod attack? be that guy." Town officials said the beach would be closed to swimming at least through Friday, and they put up signs that read, "Danger, No Swimming." A few of the nearly 40 miles (65 kilometers) of

TRURO, Mass.—On a windswept dune overlooking the Atlantic Ocean, hastily erected signs warned Cape Cod beachgoers to stay out of the water on Thursday, a day after a New York man became the first person to be attacked by a shark off the coast of Massachusetts since 2012.

The victim, William Lytton, of Scarsdale, New York, was airlifted to a hospital in Boston, where he was being treated for deep puncture wounds to his torso and leg after staggering to shore, dazed and bleeding. The hospital said Lytton, 61, remained in serious condition, and his family asked for privacy.

Police said Lytton was bitten by a shark while wading about 30 yards (27 meters) off Long Nook Beach in Truro, on the outer coastline of the peninsula. The area is part of the Cape Cod National Seashore, a major summer tourism destination.

In a scene reminiscent of the movie "Jaws," Massachusetts' foremost shark expert, Greg Skomal, planned to speak with Lytton and examine his wounds to see if he was bitten by a great white shark. Numerous great white sightings have been reported in the area, which is frequented by seals, and witnesses reported seeing seals in the water just before the attack.

Truro was the site of the last shark attack in Massachusetts, in July 2012, when a Colorado man on nearby Ballston Beach suffered a bite that required 47 stitches. The state's last shark attack fatality was in 1936.

"They're there, just as much as the sunrise and sunset. We're just guests," vacationer Steven McFadden, of Plattsburgh, New York, said as he watched waves break on the deserted beach at dawn. "I'll cool my feet off sometimes, but I'm not going to swim. I don't want to