A diver in the water near the rocks at the northern end of the beach reported seeing the first shark just after noon and notified the lifeguards on duty.

The lifeguards immediately asked everyone to get out of the water.

Despite the record-breaking heat, none of the swimmers was reluctant to leave the water.

“Everyone was very co-operative,” Lifeguard Services Australia lifeguard Bernard Robben said. 

“We had to tell people who arrived at the beach after the closure was announced that they couldn’t go in.” 

Mr Robben then went to the area of the sighting, and saw the shark for himself.

“It was about one-and-a-half-metres long,” he said.

Two hours later, the beach was almost ready for reopening when lifeguard Melanie Fitzgerald and members of the public at the beach sighted a shark of similar size at the other end of the beach.

It is not known if this was the same shark.

The beach reopened at 3.50pm, and scores of people went straight back into the water.