Two gunmen shot dead at least 16 people on Sunday during a Jewish holiday celebration at Sydney’s Bondi Beach, Australian authorities said, declaring it a terrorist attack. One gunman was fatally shot by police and the second arrested.

The suspect was in critical condition, authorities said. At least 40 people were confirmed wounded, including two police officers, said Mal Lanyon, the police commissioner for New South Wales state, where Sydney is located.

The massacre followed a wave of antisemitic attacks that have roiled Australia over the past year, although the authorities didn’t suggest those episodes and Sunday’s mass shooting were connected. They said one of the gunmen was known to the security services.

“This attack was designed to target Sydney’s Jewish community,” the state’s Premier Chris Minns said. The massacre was declared a terrorist attack due to the event targeted and weapons used, Mr. Lanyon said.

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

One dramatic clip broadcast on Australian television showed a man appearing to tackle and disarm one of the gunmen, before pointing the man’s weapon at him, then setting the gun on the ground. Mr. Minns called the man, named by relatives to Australian media as fruit shop owner Ahmed al Ahmed, a “genuine hero.”

Chabad identified one of the dead as Rabbi Eli Schlanger, assistant rabbi at Chabad of Bondi and a key organizer of the event, who has worked in the Bondi area for more than 18 years.

Chabad is an Orthodox Jewish movement that is known for its outreach to non-religious Jews. It runs scores of centers around the world that are popular with Jewish travelers and often sponsors large public events during major Jewish holidays.

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.

Mr. Lanyon said the death toll was “fluid” and that wounded people were still arriving at hospitals.

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,” Mr. 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.

Grace, 30, from Melbourne, who declined to give her last name, and her partner Joel Sargent, 30, told the AP they were in their hotel room when they heard a banging sound and looked out of their window to see people running down the street, hiding behind trees and cars.

“People were screaming, and the gun sounded so loud,” Grace said. “It was constant; it would have been over 50 (shots), easily.”

Police said their operation was “ongoing” and that a “number of suspicious items located in the vicinity” were being examined by specialist officers, including an improvised explosive device found in one of the suspect’s cars. Emergency services were called to Campbell Parade about 6.45 p.m. responding to reports of shots being fired.

Prime Minister Anthony Albanese told reporters in Canberra that he was “devastated” by the massacre.

“This is 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 evil, antisemitism, terrorism that has struck the heart of our nation,” Mr. Albanese said. “There is no place for this hate, violence and terrorism in our nation.”

Mr. Albanese said the authorities were working to identify everyone involved in the attack.

“Let me be clear we will eradicate it amidst this vile act of violence and hate will emerge a moment of national unity where Australians across the board will embrace their fellow Australians of Jewish faith,” he said. “The evil that was unleashed at Bondi Beach today is beyond comprehension, and the trauma and loss that families are dealing with tonight is beyond anyone’s worst nightmare.”

Australia, a country of 28 million people, is home to about 117,000 Jews, according to official figures. Antisemitic incidents including assaults, vandalism, threats and intimidation surged more than threefold in the country during the year after Hamas attacked Israel on October 7, 2023, the government’s Special Envoy to Combat Antisemitism Jillian Segal reported in July.

Throughout last summer, the country was rocked by spate of antisemitic attacks in Sydney and Melbourne. Synagogues and cars were torched, businesses and homes have been graffitied and Jews were attacked in those cities, where 85 percent of the nation’s Jewish population live.

Albanese in August blamed Iran for two of the attacks and cut diplomatic ties to Tehran. The authorities didn’t make such claims about Sunday’s massacre.

Meanwhile, Israel urged Australia’s government to address crimes targeting Jews.

“The heart of the entire nation of Israel misses a beat at this very moment,” Israeli President Isaac Herzog said. “We repeat our alerts time and time again to the Australian government to seek action and fight against the enormous wave of antisemitism which is plaguing Australian society.”