Sydney's iconic Bondi Beach has been closed for an hour after a news helicopter captured footage of sharks near surfers and swimmers.
Friday morning's footage appeared to show a number of sharks swimming near dozens of surfers.
A dark patch of bait fish, also known as a bait ball, was close by.
The footage was snapped by a chopper shared by media networks the ABC and Channels 7 and 9.
An ABC producer alerted Surf Life Saving NSW to the footage around 9am, with lifeguards at Bondi clearing the water shortly afterwards.
"Seeing the proximity of so many people in the water, so many surfers to the sharks, (the producer) wanted the authorities to know about that," said an SLS NSW spokeswoman.
Lifeguards closed the beach and set off an alarm to get swimmers out of the water.
They used jetskis to frighten the fish away, with the sharks following. The sharks' breed is unknown.
A couple of swimmers got a ride back to shore on the jetskis, a Waverley Council spokeswoman added.
The beach was closed for around an hour.
The SLS NSW spokeswoman said a large school of bait fish is one of the clues its drones look for while doing shark surveillance in summer.
"Usually when there are really large schools of bait fish, there's more often than not sharks in the vicinity," she said.