The two men are seen violently fighting in the lobby until the 26-year-old ultimately takes control of the assault weapon.
MONTEREY PARK, Calif. (KABC) -- Dramatic new surveillance video shows the man who disarmed the Monterey Park mass shooting suspect confronting him moments after he entered a ballroom in Alhambra.
The footage was taken just after 72-year-old Huu Can Tran entered the Lai Lai Ballroom & Studio on Saturday. You can see Tran walking into a small room near the ballroom's lobby carrying an assault pistol with an extended magazine. The gun also appears to have a large silencer on it.
Moments later, Tran is confronted by 26-year-old Brandon Tsay. The two then exchange a few words before Tsay charges at Tran. The two men are seen violently fighting in the lobby until Tsay ultimately takes control of the assault weapon, forcing Tran to run out of the door.
Tsay told ABC's "Good Morning America" that he thought he was going to die.
"Something came over me. I realized I needed to get the weapon away from him, I needed to take this weapon, disarm him or else everybody would have died," Tsay said. "When I got the courage, I lunged at him with both my hands, grabbed the weapon and we had a struggle."
Once Tsay seized the gun, he pointed it at the man and shouted: "Get the hell out of here, I'll shoot, get away, go!"
The assailant paused, but then headed back to his van, and Tsay called the police, the gun still in his hand.
Tsay did not know it at the time but would later learn that this same man had allegedly opened fire at Star Ballroom Dance Studio in nearby Monterey Park about 20 minutes earlier, killing at least 11 people and wounding 9 others.
Records indicate Tran worked as a professional trucker for at least 20 years, for a brief time running his own trucking company. He served as CEO of a business based in San Gabriel called Tran's Trucking, Inc. But it didn't stay in business long. Records indicate the business was formed in 2002 but dissolved in 2004.
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Tran's former wife, who asked not to be named, told CNN she met him about 20 years ago at Star Ballroom. Tran introduced himself at a dance and offered her free lessons. They married soon after that.
She said Tran had a short temper, though he was not violent. If she made a mistake dancing, he would get upset because he thought it made him look bad, she recalled. Court records indicate Tran filed for divorce in 2005.
Tran was an immigrant from China, according to documentation on his marriage license shown to CNN.
A former tenant and longtime acquaintance of Tran told ABC News that he was a regular at the dance studios in Monterey Park and Alhambra.
Hemet police say Tran visited the department lobby on Jan. 7 and 9 of this year. He made allegations about fraud, theft and poisoning involving his family in the Los Angeles area 10 to 20 years ago, the department said. He said he would return with documentation proving his allegations but he never showed up again.
The massacre in Monterey Park was the nation's fifth mass killing this month. It was also the deadliest attack since May 24, when 21 people were killed in an elementary school in Uvalde, Texas.
The shooting happened in the heart of its downtown where red lanterns decorated the streets for the Lunar New Year festivities. The celebration in Monterey Park is one of California's largest. Two days of festivities, which have been attended by as many as 100,000 people in past years, were planned. But officials canceled Sunday's events following the shooting.
CNN, ABC News and the Associated Press contributed to this report.