At least 11 people were killed and more than two dozen injured in a shooting by two gunmen at a Jewish holiday event at Sydney's Bondi Beach on Sunday.

Australian police have deemed the shooting a terrorist attack and are working to determine whether others were involved.

One suspected gunman was dead and another in critical condition, authorities said. A police officer is also among the dead and another was injured, New South Wales Police Commissioner Mal Lanyon confirmed at a news conference with New South Wales Premier Chris Minns.

"No stone will be left unturned," Lanyon said."This news of violence, the taking of innocent lives, is unacceptable to New South Wales."

Hundreds had gathered for an event at Bondi Beach called Chanukah by the Sea, which was celebrating the start of the Hanukkah Jewish festival.

Police said their operation was “ongoing” and that a “number of suspicious items located in the vicinity” were being examined by specialist officers.

Dramatic footage apparently filmed by a member of the public and broadcast on Australian television channels showed someone appearing to tackle and disarm one of the gunmen, before pointing the man’s weapon at him.

Witnesses said the shooting at the famed beach on a hot summer's evening lasted about 10 minutes, sending beachgoers scattering along the sand and into nearby streets and parks.

Lachlan Moran, 32, from Melbourne, was waiting for his family nearby when he heard shots, he told The Associated Press. He dropped the beer he was carrying for his brother and ran.

“You heard a few pops, and I freaked out and ran away... I started sprinting. I just had that intuition. I sprinted as quickly as I could,” Moran said. He said he heard shooting off and on for about five minutes.

“Everyone just dropped all their possessions and everything and were running and people were crying and it was just horrible,” Moran said.

Emergency services were called to Campbell Parade about 6.45 p.m. responding to reports of shots being fired.

Local news outlets spoke to distressed and bloody bystanders who witnessed the horror. New South Wales Premier Chris Minns described the reports and images coming from the scene as “deeply distressing.”

Prime Minister Anthony Albanese said the shooting was a"targeted attack on Jewish Australians on the first day of Hanukkah, which should be a day of joy, a celebration of faith — an act of antisemitism, terrorism that has struck the heart of our nation."

Albanese was speaking to reporters with Australian federal police assistant commissioner Nigel Ryan.

"An attack on Jewish Australians is an attack on every Australian," Albanese said."What was unleashed today is beyond comprehension and the trauma and loss that families are dealing with tonight is beyond anyone's worst nightmare."

Israeli President Isaac Herzog said Jewish people who had gone to light the first candle of the Hanukkah holiday on the beach had been attacked by"vile terrorists."

Israeli Foreign Minister Gideon Saar said he was appalled by the shooting and that Australia's government must "come to its senses" after countless warnings.

"These are the results of the antisemitic rampage in the streets of Australia over the past two years, with the antisemitic and inciting calls of 'Globalize the Intifada' that were realized today."

One of the world's most famous beaches, Bondi is typically crowded with locals and tourists.

"If we were targeted deliberately in this way, it's something of a scale that none of us could have ever fathomed. It's a horrific thing," Alex Ryvchin, co-chief executive of the Executive Council of Australian Jewry, told Sky News, adding his media adviser had been wounded in the attack.

Riley Stranaghan, a Canadian living at a hostel on Bondi beach, was at the beach with a friend when the pair heard the gunshots.

"I told him, 'No, those aren't fireworks, those are gunshots,' and then everyone just starts sprinting off the beach and obviously we did the same and we just ran and ran," he told CBC News.

Stranaghan ended up sheltering in a stranger's apartment for a couple hours.

"I just remember running down the street and seeing kids cry, families running," he said."It was terrible."

Prime Minister Mark Carney reacted to the shooting on X.

"Horrified by the antisemitic terror attack that has stolen the lives of 12 people at a Hanukkah event on Bondi Beach today in Australia," Carney wrote.

"Canada stands with the people of Australia and Jewish people everywhere in sorrow, and determination never to bow to terrorism, violence, hatred and intimidation."

WATCH | Witness describes 'traumatic' scene at Bondi beach:

Bondi Beach attack: Canadian witness recounts running to safety

2 hours ago|

Duration 7:30

Riley Stranaghan, a Canadian staying in Sydney, Australia, said he was with a friend on Bondi Beach when they heard loud noises they initially mistook for fireworks. Multiple people are dead and many others are injured after Sunday's shooting at an event celebrating the start of the Hanukkah Jewish festival.

Bystander who tackled gunman hailed as hero

The footage of the bystander's actions spread quickly on social media as people praised the man for his bravery, saying his actions had potentially saved many lives. His identity was not immediately known.

"Australian hero (random civilian) wrestles gun off attacker and disarms him. Some people are brave and then some people are ... whatever this is," one person said on the X platform, sharing the video.

Minns, the premier of New South Wales state, said it was the"most unbelievable scene I've ever seen."

"A man walking up to a gunman who had fired on the community and single-handedly disarming him, putting his own life at risk to save the lives of countless other people."

"That man is a genuine hero, and I've got no doubt that there are many, many people alive tonight as a result of his bravery."

Albanese praised the actions of Australians who had "run towards danger in order to help others."

"These Australians are heroes and their bravery has saved lives," he said at the Canberra news conference.

Mass shooting deaths in Australia are extremely rare. A 1996 massacre in the Tasmanian town of Port Arthur, where a lone gunman killed 35 people, prompted the government to drastically tighten gun laws and made it much more difficult for Australians to acquire firearms.

Significant mass shootings this century included two murder-suicides with death tolls of five people in 2014, and seven in 2018, in which gunmen killed their own families and themselves.

In 2022, two police officers were shot and killed by Christian extremists at a rural property in Queensland state. The three shooters in that incident, conspiracy theorists who hated the police, were also shot and killed by officers after a six-hour siege in the region of Wieambilla, along with one of their neighbours.