This is the bizarre moment beachgoers played volleyball just yards away from a surfer critically injured in a shark attack in Sydney.

Footage shows locals engrossed in their matches as lifeguards resuscitated the wounded man on the shore of North Steyne Beach in Manly, New South Wales, on January 19.

Local media reported that the man had been pulled unconscious after a horror shark attack that left him with a mangled right calf.

He had reportedly lost a significant amount of blood and went into cardiac arrest before intensive care paramedics arrived on a Toll NSW Ambulance Rescue Helicopter. He was treated and rushed to Royal North Shore Hospital, where he is fighting for his life.

In a statement, the New South Wales police said: 'The man, believed to be aged in his 20's, was treated for serious leg injuries by NSW Ambulance paramedics and taken to Royal North Shore Hospital in a critical condition.

'All beaches on the Northern Beaches are closed until further notice, and this will be reviewed on an ongoing basis.'

The incident is the third of four shark attacks off the coast of Sydney within 48 hours.

On Sunday, a boy, 12, was left in critical condition after being bitten near Nielsen Park.

On Monday, an 11-year-old surfer was attacked by a shark at Dee Why. While on Tuesday, a 39-year-old man suffered minor injuries when a shark bit through his surfboard at Crescent Head.

Authorities said the consecutive attacks occurred after days of heavy rain, which can attract sharks closer to shore as runoff flushes nutrients into the water.

Officials said the exact shark species involved is not yet clear, but believe notoriously aggressive bull sharks to be the culprits.

Steve Pearce, chief of the rescue service Surf Life Saving NSW, said: '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 conducive to bull shark activity. We have two people critically injured in hospital this morning. Just go to a local pool, because at this stage, we're advising that the beaches are unsafe.'

Bull sharks are large, aggressive sharks known for their ability to live in both saltwater and freshwater. They are considered one of the most dangerous shark species to humans due to their size, strength, and unpredictable behaviour.