A surfer had minor injuries from being bitten by a shark Tuesday in the fourth attack off the coast of Australia's most populous state in three days. The series of attacks have prompted beach closures and warnings that swimmers should avoid the open water and go to a pool instead.

The shark attacked the man's surfboard at Point Plomer, 290 miles north of the New South Wales state capital, around 9 a.m., police said in a statement.

The man was lucky to survive with minor cuts, Kempsey-Crescent Head Surf Life Saving Club captain Matt Worrall said.

"The board seemed to take most of the impact," Worrall told Australian Broadcasting Corp. "He made his own way into shore where he was assisted by locals."

The bystanders drove the 39-year-old man to a hospital and he was later discharged.

In the earlier attacks, a man and a boy suffered critical leg wounds and the surfboard of another boy was bitten by sharks at Sydney locations Sunday and Monday.

Beaches along New South Wales' northern coast and northern Sydney were closed Tuesday and local authorities said Sydney's northern beaches would remain closed to swimmers and surfers for 48 hours. Electronic drumlines that alert authorities when a large shark has taken bait were deployed off the Sydney coast.

Authorities warned that recent rainfall has left the water off area beaches murky, which increased the risk of bull shark attacks. Bull sharks are responsible for most attacks around Sydney.

"If anyone's thinking of heading into the surf this morning anywhere along the northern beaches, think again. We have such poor water quality that's really conducive to some bull shark activity," Surf Life Saving NSW chief executive Steve Pearce said.

"If you're thinking about going for a swim, just go to a local pool because at this stage, we're advising that beaches are unsafe," Peace added.

Police say boy's friends saved his life  

On Sunday, a 12-year-old boy was attacked after jumping from a 20-foot ledge known as Jump Rock near Shark Beach inside Sydney Harbor. Police have credited the boy's friends with saving his life by jumping from the cliff during the attack and dragging him back to shore.

"Those actions of those young men are brave under the circumstances and very confronting injuries for those boys to see," Supt. Joseph McNulty said.

News media have reported that the boy lost both legs in the attack.

Around noon Monday, an 11-year-old boy was on a surfboard that was attacked by a shark at Dee Why Beach, an ocean beach north of Manly. The shark bit off a chunk of the board, but the boy escaped uninjured.

A surfer in his 20s was bitten on a leg by a shark off North Steyne Beach on the Pacific Ocean coast in the northern suburb of Manly at 6:20 p.m. Monday, police said. Bystanders pulled him from the water before an ambulance took him to a hospital in a critical condition.

All three Sydney beaches have some form of shark protection netting. It was not immediately clear where the attacks occurred in relation to that netting.

Pearce said the scene of the latest attack was isolated and did not have shark netting.

Dee Why Beach is close to the beach where 57-year-old surfer Mercury Psillakis  was killed by a suspected white shark last September.

In November, a 25-year-old Swiss tourist was killed and her partner was seriously injured trying to save her as they swam off a national park north of Sydney.

There have been more than 1,280 shark incidents around Australia since 1791, of which more than 250 resulted in death, according to a database of the predators' encounters with humans. The International Shark Attack File, a database of global shark attacks run by the University of Florida, noted that a "disproportionate" amount of people died from shark bites in Australia in 2023 when compared with other countries around the world.

Two Americans have been killed by sharks in the past month. Less than two weeks ago, 56-year-old woman from Minnesota died after a shark attack in the U.S. Virgin Islands. 

Earlier this month, authorities in California confirmed that 55-year-old Erica Fox died from a shark attack after she went missing in Monterey Bay in late December. The coroner determined Fox died from "sharp and blunt force injuries and submersion in water due to a shark attack."