Two emergency responders who were at the scene in the immediate aftermath of Sunday evening’s mass shooting in Sydney, Australia, described a harrowing scene of anguish and chaos, brightened only by members of the community rushing over to help.

Kaitlin Davidson, a 28-year-old nurse, said she saw the shooting unfolding at Bondi Beach from the window of her ground-floor apartment, which is just across the street from the bridge where the two gunmen unleashed rounds of fire.

“They just kept reloading,” she said. “They had a ridiculous amount of ammunition and multiple guns.”

The two gunmen, whom police identified on Monday as a 50-year-old man and his 24-year-old son, attacked a festival marking the first night of the Jewish holiday Hanukkah, killing at least 15 people and wounding dozens of others.

As soon as the shooters appeared to be incapacitated, Ms. Davidson said, she ran over to help, as the police were occupied making sure the gunmen were contained. Ambulances were having trouble getting to the scene because people had abandoned their cars in the intersection to flee, she said.

One female officer had been shot in her bulletproof vest, which Ms. Davidson said she had pulled off to make sure the officer was not seriously harmed. Other people nearby led Ms. Davidson to the other side of the bridge, where the Hanukkah event had been taking place.

“It was a war zone,” Ms. Davidson said.

She treated about half a dozen people with gunshot wounds to the legs, butt or shoulders. At least one person was shot in the back, seemingly as they were running away, she said.

David Smith, 25, is a volunteer with Community Health Support, a Jewish organization that responds to those in medical need. A lifelong resident of Bondi Beach, he was dispatched by the group to head to the scene of the shooting, he said.

He went from patient to patient, assessing their injuries and tagging them based on the priority of their medical need — red for the most urgent, which included more than 20 victims. People were screaming and children were looking for their parents, he recalled, as some of the injured cried out in dismay that they had done nothing to deserve this.

He was on the scene for three to four hours, Mr. Smith said. Because of how tight-knit Bondi’s Jewish community is, he knew three of the dead and three of the injured who were still in the hospital, he said.

The tragedy was all the more unfathomable because the scenic beach has been the backdrop to his everyday routines for as long as he can remember, he said.

“This is my morning run, this is my afternoon swim,” he said.

Victoria Kim is the Australia correspondent for The New York Times, based in Sydney, covering Australia, New Zealand and the broader Pacific region.