'Catastrophic injuries': Swimmer killed in suspected Sydney shark attack

Human remains have been found after a suspected shark attack in Sydney's south-east.

Emergency services responded to reports a swimmer had been attacked by a shark at Little Bay Beach near Malabar about 4.30pm today.

Officers found human remains in the water.

A swimmer has been fatally attacked by a shark at Little Bay Beach. Human remains have been found after a suspected shark attack in Sydney's south-east.

Witnesses said they heard the swimmer yelling.

"Some guy was swimming and a shark came and attacked him vertically," Kris Linto, a witness, said.

"We heard a yell and turned around 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."

"It was really bad."

Mr Linto claimed he saw a 4.5-metre great white shark attack the swimmer.

Paramedics said the swimmer had suffered 'catastrophic' injuries. A police helicopter joined the search for the victim and the shark. Police joined volunteers, paramedics and lifeguards in the search for the swimmer.

NSW Ambulance Inspector Lucky Phrachanh said the swimmer could not be saved.

"Unfortunately, this person had suffered catastrophic injuries as a result of the attack and there was nothing paramedics could do when we arrived on scene," he said.

Police were called to the beach, near Malabar, about 4.30pm.

Little Bay Beach has been closed as police search the area.

Police will liaise with the Department of Primary Industry to investigate the circumstances of the death.

A report will be prepared for the Coroner.