A Cape Cod National Seashore beach was temporarily closed to swimming after visitors and lifeguards saw a shark about 30 yards offshore.

Chief Ranger Leslie Reynolds tells the Cape Cod Times Marconi Beach was closed at about 1 p.m. Monday. Reynolds said the shark moved north along the beach for about 10 minutes, staying on top of the water in behavior similar to a basking shark.

Reynolds said the beach was reopened an hour later after no more sightings were reported. It was the first confirmed sighting off the National Seashore this summer.

Nauset Beach was closed for an hour in June after a great white shark sighting. Great whites have been seen off Cape Cod in recent years, apparently hunting for seals.

A great white bit a man swimming off Truro's Ballston Beach last year.

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