In Truro, Mass., what's believed to be the first attack by a great white shark in 76 years frightened beachgoers and sent a man to the hospital this week.

Greg Skomal, a state biologist, said that eyewitness reports of the attack and the fact that seals were prevalent on the beach, makes him almost certain the attacker was a great white. “We can conclude that it’s highly likely,” he said.

Chip Douglas from Lancaster was one of those eyewitnesses on Ballston Beach during the attack on July 30.

“We were like right here, and then someone screamed 'Help!' and then a bunch of people jumped in and dragged him in,” Douglas said. “I went over — they banded up his left leg but I saw his right leg. I knew it was a shark just because it was such a big bite. It was that big with a bunch of puncture wounds that you could put your finger in.”

The attack has put a scare into some families vacationing on the Cape.

At Ballston Beach, only about four people were in the ocean on Aug. 1, and even those beachgoers only ventured a few feet into the water.

Tricia Seidel and her young children are visitors from California, and the family has spent its past 40 summers here on Cape Cod. After the attack, Seidel made sure that her children were careful as they went into the water.

“Well, if you notice, the kids are playing on the edge, but they're not going in,” Seidel said. “And if Daddy was here, he might take them in a little farther, up to about here, the knee, and only if other people are in the water as well.”

Seidel's 10-year-old son, Robert, had no problem with that.

“I'm a very emotional person, and I don't like to see scary things,” he said. “Knowing that this is probably my favorite beach in Cape Cod, knowing that there was a shark here is sort of — it's creepy, because I always swim out in the deep.”

Nine great whites already have been spotted off the coast of Cape Cod this summer. Many experts blame the increase of shark numbers on the Cape's growing population of seals: a favorite meal of great whites.