SYDNEY -- At least 12 people have died after a shooting at Sydney's Bondi Beach on Sunday night, said New South Wales Premier Chris Minns.

One of the offenders was among the dead and another one is in custody, the Australian Broadcasting Corporation (ABC) cited Minns as saying.

NSW Police Commissioner Mal Lanyon declared the attack to be "a terrorist incident."

The state's ambulance service said that 16 people had been taken to hospital, with several others treated at the scene.

A second gunman was among those taken to hospital. At least two police officers were also injured.

Nine Network television reported that up to 20 people had been shot.

Authorities said there is no longer an active threat but have urged people to avoid the area.

One of the gunmen was Naveed Akram from Bonnyrigg in Sydney's south-west, the ABC reported, quoting a senior law enforcement official.

The official, speaking on condition of anonymity, said Akram's home in Bonnyrigg is currently being raided by police.

Many members of the Jewish community had assembled at the beach to celebrate Hanukkah, the Jewish Festival of Lights, earlier in the evening.

A Hanukkah event in Melbourne has been cancelled, and the Jewish community there is on high alert following the mass shooting in Sydney, the local Herald Sun newspaper reported.

The shooting occurred at around 6:40 pm local time when at least two men armed with high-powered guns opened fire on a crowd of people.

A warning issued by police shortly before 7 pm advised members of the public to avoid the area and for anyone at the scene to take shelter.

Video footage and photographs from the scene showed people fleeing from the beach and firearms lying on the ground.

Australian Prime Minister Anthony Albanese said in a statement that the scenes at Bondi are "shocking," and NSW Premier Chris Minns described the incident as deeply distressing.