Several beaches in Sydney, including the iconic Bondi and Bronte, were shut down on Thursday after a swimmer was killed in a shark attack, the first such fatality at the city's beaches in nearly 60 years.

Drum lines, which are used to bait sharks, have been set up near the attack site while drones have been deployed as officials search if the shark is still in the area.

A video shared online showed a shark attacking a person on Wednesday afternoon off Little Bay beach, about 20km south of Australia's largest city and near the entrance to Botany Bay. Police have not yet disclosed the identity of the swimmer.

“This has been a complete shock for our community,” Dylan Parker, the mayor of Randwick Council which includes Little Bay, told Reuters. “Our coastline is our back yard and to have a tragic death under such horrifying circumstances is completely shocking.”

The attack comes days before the Murray Rose Malabar Magic Ocean Swim, an annual charity event usually attended by thousands of swimmers at a neighbouring beach. Organisers said they were monitoring the situation and if the event had to be postponed it would be held on March 6.

A spokesperson for the New South Wales Department of Primary Industries said its shark biologists believe that a white shark at least 3m in length was likely responsible for the attack. It was the first fatal shark attack near Sydney since 1963, data showed.

Authorities have ordered people to remain out of the water on a hot summer day as temperatures hovered around 30°C.

“A few crazy surfers still go out and take the risk but most of us take notice and just stay out of the water until the sharks have gone. It's a lot more dangerous driving to be quite honest,” local resident Karen Romalis told Reuters.