Australian authorities report that the human remains were found after they arrived in response to a shark attack.
Sydney had its first fatal shark attack in decades this past Wednesday.
According to a database compiled by the Taronga Conservation Society, there were three fatal shark attacks in Australia last year, including two in New South Wales, but none in the city of Sydney since 1963.
Authorities said human remains were discovered after the horrifying incident.
“This person had suffered catastrophic injuries as a result of the attack and there was nothing paramedics could do when we arrived on scene,” New South Wales state Ambulance Inspector Lucky Phrachnanh said.
"An investigation into the swimmer's death is ongoing, and Little Bay Beach is closed as officers continue to search the area," the New South Wales police said in a statement.
A man fishing off nearby rocks told national broadcaster ABC he saw a man in a wetsuit being dragged underwater by a large shark off the eastern suburbs beach of Little Bay.
"When he went down there were so many splashes," a man who had seen the incident take place said to ABC.
The witness described the shark as a Great White about 15-feet-long.
"It was terrible. I am shaking," he said, describing the attack as having lasted several moments.
"Some guy was swimming and a shark came and attacked him vertically," Kris Linto, another witness, told Nine News. "We heard a yell, turned around, and it looked like a car had landed in the water, a big splash then the shark was chomping at the body and there was blood everywhere."
Investigators are working with the state's Department of Primary Industries to investigate the details surrounding the swimmer's death. The state coroner will prepare a report.
In addition to only swimming in monitored areas of the beach, Surf Life Saving NSW advises people to avoid swimming at dawn, dusk and night.
The organization also suggests avoiding schools of baitfish and river mouths or murky water, and police are urging residents and beachgoers to heed the organization’s safety advice.
