Father and son gunmen kill 15 at Jewish festival on Australia's Bondi Beach

A father and son opened fire on a Jewish festival at Australia's Bondi Beach in a shooting spree that killed 15 people, including a child, authorities said on Monday, denouncing the attack as antisemitic "terrorism."

The pair fired into crowds packing the world-famous Sydney beach for the start of Hanukkah on Sunday evening, sending people fleeing in panic.

A 10-year-old girl was among those killed in Australia's worst mass shooting for almost three decades. Another 42 people were rushed to hospitals with gunshot wounds and other injuries.

Police are still unravelling what drove the shootings, although authorities have said the plot was clearly designed to sow terror among the nation's Jews.

"What we saw yesterday was an act of pure evil, an act of antisemitism, an act of terrorism on our shores," Prime Minister Anthony Albanese said before laying flowers at the Bondi Pavilion.

The Australian Broadcasting Corporation said the father and son had possible links to the Islamic State group.

The gunmen targeted an annual celebration that drew more than 1,000 people to the beach to mark the Jewish festival.

They took aim from a footbridge looking over the beach, which was packed with swimmers cooling off on a steamy summer evening.

Carrying long-barreled guns, they peppered the area with bullets for 10 minutes before police shot and killed the 50-year-old father.

The 24-year-old son was arrested and remained under guard in the hospital with serious injuries.

Police later found a homemade bomb in a car parked close to the beach, saying the "improvised explosive device" had likely been planted by the pair.

Wary of reprisals, police have so far dodged questions about the attackers' religion or ideological motivations.

"We want to get to the bottom of this. We want to understand the motives behind it," said New South Wales police commissioner Mal Lanyon.

Misinformation spread quickly online in the wake of the attack, some of it targeting immigrants and the Muslim community.

Police also said they had responded to reports on Monday morning of several pigs' heads being left at a Muslim cemetery in southwestern Sydney.

AFP