Several Sydney beaches, 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 for 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 20 km (12 miles) 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 backyard and to have a tragic death under such horrifying circumstances is completely shocking."

A charity ocean swim at a nearby beach scheduled for Sunday was cancelled out of respect for the victim and family. Organisers of the Murray Rose Malabar Magic Ocean Swim had considered postponing the swim till March, but said they decided to cancel it after consulting with the local council and lifesavers.

A spokesperson for the New South Wales Department of Primary Industries said its shark biologists believe that a white shark at least 3 metres (9.8 feet) in length was likely responsible for the attack. It was the first fatal shark attack in 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 degrees Celsius (86 degrees Fahrenheit).

"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.