ABC News' Daniel Rapaport reports:

When rescuers reached shark attack victim Jana Witteropp, only a bone was left where her right arm had been.

Witteropp, 20, was attacked by a shark about 75 feet offshore of Palauea Beach off Maui, Hawaii, on Wednesday. The shark had bitten her just below the shoulder.

"As we were walking up to the beach we heard this scream, this blood-curdling scream out in the water," Rick Moore, 57, of Orange County, Calif., told ABC affiliate KITV.

Moore, a high school teacher and pastor, headed directly to Witteropp. A nightmarish scene greeted him as he approached the bloody victim.

"All she had hanging out on her right arm was her bone, and she was in and out of saying these words, 'I'm dying, I'm going to die,'" Moore said. "I kept saying 'No you're not, you're not, I'm going to get you to shore, I'm going to save you.'"

READ MORE: Shark Attack Off Hawaiian Coast Costs Tourist an Arm

He carried Witteropp, who was fading in and out of consciousness due to a loss of blood, back toward shore. Nicholas Grisaffi, visiting from Laguna Beach, Calif., met the two of them in the water and assisted in the rescue effort.

"I went out in about neck-deep water," Grisaffi told KITV. "As soon as he got to me I was able to grab his arm. And he was able to still hold on to her and I pulled them up to waist-deep water."

While waiting for help to arrive, Moore performed CPR on Witteropp in an attempt to keep her conscious and breathing.

Witteropp was taken to Maui Memorial Medical Center where she remains in critical condition.

Experts are looking into an unusually high volume of shark attacks off Maui in recent years. Last year saw 11 shark attacks on the Hawaiian islands, six of which, occurred in Maui. This year, there have been eight attacks throughout the islands with five taking place in Maui.

"The questions are: Is there anything different around Maui?" Russell Sparks with Hawaii's Department of Land and Natural Resources told KITV. "The habitat is different, there are several islands and they are connected with shallower water depths than other islands, so maybe that's affecting shark behavior."

(KITV)