Witness accounts and videos verified by The New York Times show how gunmen killed at least 15 people on Sunday at a Jewish celebration at Bondi Beach in Sydney in what the authorities called a terrorist attack.

Two suspects opened fire from a footbridge at hundreds of people who had gathered for a Hanukkah celebration. At one point, after one of the shooters walked down from the bridge, a bystander grabbed the gunman from behind and wrested his gun away before pointing it back at him, according to videos and witness accounts.

Police arrived and opened fire at the gunmen, videos show. One of the shooters was killed, the police said, and the other was wounded and in custody.

When the gunmen arrived, they emerged from a small silver hatchback parked by the footbridge. They fired on people nearby and killed at least two, according to a witness who tried to help the victims.

The gunmen then proceeded to the high ground of the bridge with three long guns, visible in several videos, and fired into the crowd in the park.

After about a minute, one gunman wearing white pants descended from the bridge, videos and witnesses confirmed. He continued shooting as he walked toward the crowd gathered for the Hanukkah celebration, which featured free donuts and music.

The gunman on the bridge wearing black pants kept firing. He waved away beachgoers swearing at him, telling them to go, witnesses said, as he shot at the crowd that had gathered for the holiday festival.

A man who had been sheltering between parked cars is seen in one video rushing toward the gunman with the white pants, who continued to draw nearer to the Hanukkah event. The man wrestled the rifle from him and aimed it at the gunman, who retreated to the bridge.

Shortly afterward, the police began to fire at the gunmen. In videos, they can be seen ducking to avoid incoming fire before the man in white pants appears to be hit, and collapses.

The man in black pants kept firing at the police for another minute, videos show and witnesses confirmed, shooting from both sides of the bridge before he appears to be shot as well.

“He’s down, he’s down,” a witness yelled in a video that captured most of the incident.

In the area where the Hanukkah festivities were held, several victims could be seen in witness video lying on the ground, apparently lifeless. Witnesses described a scene of sadness and sudden triage. Civilians, security guards for the Hanukkah event and lifeguards administered CPR as ambulances carried away those who had been killed and wounded.