A 26-year-old coder wrested an assault pistol from the gunman’s hands, preventing a greater tragedy.

His older sister, Brenda, who currently runs the business, said the video showed a fierce and prolonged fight between the two men throughout the lobby.

“He kept coming at him, he really wanted to get the gun back,” he said of the gunman.

The younger Mr. Tsay, a computer coder who mans the box office a few days a week at the dance hall founded by his grandparents, said that around 10:35 p.m. Saturday he turned on the gunman, whom he did not acknowledged. . He had never seen a real weapon before, but he realized it was a deadly weapon, he said.

“My heart sank, I knew I was going to die,” he said.

The next moment, he lunged forward and grabbed the gun by the barrel and began wrestling with the gunman for control of it.

“That moment, it was a primal instinct,” he said. “Something happened there. I do not know what happened to me”.

They wrestled for control of the weapon for about a minute and a half, and it appeared they were of similar strength, Tsay said. At one point, the gunman looked at the gun and removed one hand from it, as if he was going to manipulate the gun to start shooting. Mr. Tsay said he seized the moment and took the gun from the man.

He pointed the gun at him and yelled, “Go away, get out of here,” he recalled.

Mr Tsay, who stayed up all night helping police with their investigation, said he felt traumatized and had been unable to process what had happened. In particular, he was heartbroken for the Monterey Park community and the surrounding areas where his family and his ballroom had established themselves as a beloved haven for three decades, he said.

“Lai Lai,” a name her grandmother chose, means “come, come” in Chinese, her sister said. The assailant, dressed in black, looked like he could easily be one of her regular customers, she said.

“We have a very tight-knit community of dancers,” she said. “It feels so terrible that something like this happened, for one of our individuals to try to harm others.”

shawn hubler contributed reporting.