Sydney: Authorities have shut down beaches across northern Sydney after a surfer in his 20s was critically injured in a shark attack, the third such incident in just two days.

Emergency services were called to Manly Beach on Monday evening after reports that a shark had bitten the young man. He suffered severe leg injuries and was rushed to hospital, where he remains in critical condition, New South Wales police confirmed.

All beaches in the Northern Beaches council area will stay closed until further notice as a precautionary measure.

Earlier on Monday, a 10-year-old boy narrowly escaped harm when a shark knocked him off his surfboard, leaving a large bite mark on the board but sparing the child. On Sunday, another boy was left in critical condition after being attacked at a city beach.

Marine experts believe recent heavy rainfall may have contributed to the surge in shark activity. Runoff into the harbour and coastal waters has created conditions favourable for bull sharks, a species that thrives in brackish water.

Australia records around 20 shark attacks annually, with fewer than three resulting in fatalities, according to conservation groups. Despite the recent cluster of incidents, experts note that drownings remain a far more common cause of death on the country’s beaches.