He was reportedly surfing with friends when the attack happened just 100 metres (330ft) from the shore.The man lost both his legs while his surfboard was cut in half, the Herald reported. It was not yet known what species of shark was responsible for the attack.Images of the scene on local media showed police gathered on the shore and ambulances parked nearby. Drones were scanning the beach for shark activity, according to Australian public broadcaster ABC.The victim was bitten by the ocean predator while surfing in the morning away from a patrolled area of the beach, according to Surf Life Saving NSW.Beaches between the northern suburbs of Manly and Narrabeen have been closed for at least 24 hours, it said. Surf life-saving clubs nearby have cancelled all water activities and training for the weekend.An unnamed surfer said the victim had been surfing off the adjoining Long Reef and Dee Why beaches. "Four or five surfers pulled him out of the water and it looked like a significant part of his lower half had been attacked," the surfer said, according to Sydney's Daily Telegraph.