SYDNEY: A shark killed a man as he swam off a popular beach near Perth in Western Australia on Friday (Sep 18), police said.

It was the fourth death from a shark attack in Australia this year.

"It was reported a male swimmer had been bitten by a shark while swimming along the coast," a Western Australia state police spokeswoman said in a statement.

"The swimmer died as a result of the attack."

Police helicopters and boats scoured waters off Sorrento Beach after emergency services were called to the beach in the morning, officials said.

Authorities closed beaches in the area until further notice.

Local media reported that witnesses had seen blood in the water.

"It was like a scene off Jaws where a body is flicked around like a rag doll," an unidentified male witness on the beach told local broadcaster Seven.

Surf Life Saving WA said in a social media post that an unidentified species of shark was involved in the incident about 50m offshore.

It was the second shark attack in Western Australia this week, after a man lost part of his leg when he was bitten at Glenfield Beach, north of Perth.

There have been multiple shark attack fatalities around the country this year.

A 12-year-old boy died after he was bitten by a shark while swimming in Sydney Harbour in January.

Three divers were fatally mauled in separate incidents between May and June - two in Western Australia and the third in Queensland.

Also in June, a woman had to have part of her left arm amputated after she was mauled by a shark at one of Australia's most popular beaches, Coogee, in Sydney.

There have been around 1,300 shark incidents around Australia since 1791, of which more than 260 resulted in death, according to a database of their encounters with humans.