A surfer who died after being mauled by a shark at a Sydney beach was a loving husband and father to a little girl, as new details about the attack emerge. 

Mercury Psillakis, 57, is believed to have lost both his legs before his body was brought to shore by surfers at Dee Why beach just after 10am on Saturday.

'He was retrieved from the surf and brought to the shore; however, died at the scene,' NSW Police said in a statement. 

Mr Psillakis, a twin, was an experienced surfer and local to the area. He was reportedly only in the water for 30 minutes before the attack. 

A shark alarm was triggered at the beach, which has a shark net installed. 

A witness told Daily Mail they saw a group of people 'crying in a circle' just metres from the water. It is understood one of Mr Psillakis' relatives collapsed into the sand, while another was supported by loved ones.

Beaches between Manly and Narrabeen will remain closed for at least 24 hours. 

Inspector Stuart Thomson from the Northern Beaches Police Area Command said Mr Psillakis had lost 'a number of limbs' in the fatal attack. 

Mr Psillakis is pictured with his wife Maria before he lost his life one day before Father's Day

Mr Psillakis is pictured with his wife Maria before he lost his life one day before Father's Day

Mercury Psillakis, 57, has been identified as the victim of the fatal shark attack

Mercury Psillakis, 57, has been identified as the victim of the fatal shark attack

Family members are seen being consoled at Dee Why Beach following the attack

Family members are seen being consoled at Dee Why Beach following the attack

'His body was found floating in the surf, and a couple of other people went out and recovered it but attempts to save his life were unsuccessful,' he said. 

'We understand he leaves behind a wife and a young daughter - with tomorrow being Father's Day, it's particularly tragic.'

Two sections of a surfboard have been recovered and have been taken for expert examination. 

Surf Lifesavers advised Dee Why Beach would be closed until further notice. 

'Officers attached to Northern Beaches Police Area Command have closed the beach and will liaise with experts... to determine the species of shark involved,' police said. 

'Two sections of a surfboard have been recovered and taken for expert examination.

It's understood authorities have been searching for the shark as far south as North Steyne, a distance of about five-and-a-half kilometres. 

A young surfer was left shaken after he got out of the water at nearby North Narrabeen beach just hours before the attack. 

The shark alarm went off at North Narrabeen at 5.30am. 

A woman is seen being assisted by friends at the scene of the fatal mauling

A woman is seen being assisted by friends at the scene of the fatal mauling

Surfers and locals are seen at the scene of the first fatal shark attack in Sydney since 2022

Surfers and locals are seen at the scene of the first fatal shark attack in Sydney since 2022

It's understood Mr Psillakis died from lower body injuries after being brought to shore

It's understood Mr Psillakis died from lower body injuries after being brought to shore

A marine safety vessel could be seen scouring the waters where, normally, dozens of surfers wait for waves at the popular break. 

A witness who lives in nearby Long Reef told Daily Mail she saw 'at least four helicopters flying overhead in just 10 minutes'. 

The last fatal shark attack in Sydney was in 2022, when a local diver was killed by a great white shark in Little Bay. 

Shark nets at Dee Why went up in the beginning of September, but Long Reef – to its north - is not netted. 

Police are still working to identify the species of the shark involved in the attack. 

Police are still working with the Department of Primary Industries to identify the species of the shark involved in the attack (pictured, detectives on the closed beach on Saturday)

Police are still working with the Department of Primary Industries to identify the species of the shark involved in the attack (pictured, detectives on the closed beach on Saturday)

It is understood authorities are canvassing a more-than five kilometre stretch of coastline looking for the shark (pictured, a sign on Dee Why Beach on Saturday)

It is understood authorities are canvassing a more-than five kilometre stretch of coastline looking for the shark (pictured, a sign on Dee Why Beach on Saturday)