MAUI >> The California man killed by a shark off Maui over the weekend was a frequent visitor to the islands and an avid scuba diver who had recently retired, a friend said.

A shark attacked 65-year-old Dr. Thomas Smiley of Granite Bay, Calif., while he was swimming Saturday in the Kaanapali Beach Park area, police said.

A witness said that when rescuers pulled Smiley to shore and began CPR, he was missing a leg from the knee down.

Witness Allison Keller told Hawaii News Now that the man appeared unconscious when he was pulled from the water.

“As we got closer, I saw some blood on his stomach, and then I got looking a little bit more, and his wrist — it looked like the skin on his wrist was just torn off,” Keller said. “And then I got looking closer, and his entire left leg from his knee down was just missing.”

Smiley was swimming about 60 yards from shore when the attack happened, authorities said.

He died at the scene.

The state Department of Land and Natural Resources put up shark-warning signs at Kaanapali Beach Park following the attack, but following standard protocol, the signs were removed at noon Sunday.

It was the sixth shark attack reported, and first fatal shark attack, so far this year. The last fatal shark attack in Hawaii was in 2015 when a snorkeler off Maui was killed.

According to a company website, Smiley was a co-founder of Sacramento Contact Lenses and Optometry in 1982, a family practice. He held a doctorate degree from the UC Berkeley School of Optometry and completed his residency at Letterman Hospital, U.S. Army Presidio in San Francisco.

The biography also said he was an accomplished water-skier, antique and muscle car expert and stock car racer.

California media sources said Smiley had just retired and that he leaves behind a wife, three children and six grandchildren.