Sixteen people - including a gunman - have been killed after a father and son opened fire at a Jewish holiday celebration at Sydney's Bondi Beach.

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Australian officials described it as a targeted, anti-semitic terror attack.

Authorities said far more people would have been killed were it not for a bystander, identified by local media as fruit shop owner Ahmed al-Ahmed, 43, who was filmed charging a gunman from behind, grappling with him and wresting a rifle from his hands.