By AMY TAXIN, STEFANIE DAZIO, TERRY TANG and BRIAN MELLEY

MONTEREY PARK, Calif. (AP) — Investigators searching for a motive Monday in the worst mass shooting in Los Angeles County history said the gunman was previously arrested for illegally possessing a firearm, had a rifle at home, hundreds of rounds of ammunition and appeared to be manufacturing gun silencers.

Los Angeles Sheriff Robert Luna said investigators had not yet established why 72-year-old Huu Can Tran gunned down patrons Saturday night at a ballroom dance hall in Monterey Park, where tens of thousands attended Lunar New Year festivities earlier that evening. Tran later killed himself as police closed in on him.

“What drove a mad man to do this? We don’t know, but we intend to find out,” Luna said.

A man who said he had been a longtime friend of Tran told The Associated Press that the gunman once frequented the dance hall and another that he also targeted and griped about the way he thought people treated him there.

Tran fired 42 rounds at the Star Ballroom Dance Studio, killing 11 people and wounding nine. He then drove to another nearby dance hall where an employee wrestled a modified 9 mm submachine gun-style semi-automatic weapon away from him, Luna said.

Gov. Gavin Newsom met Monday with Brandon Tsay, who works part-time at the dance club founded by his grandparents, and said he was a true hero.

“This remarkable young man who without any hesitation — though with moments of fear — took it upon himself to save countless lives,” Newsom said. “Who knows how many lives he saved.”

Tsay said he was proud of his actions but did not want to discuss them so the focus would stay on the victims.

“Some of these people I know personally,” Tsay said outside his family’s home. They come to our studio. It’s a tight knit community and I hope they can heal from this tragic event”

Tran fatally shot himself Sunday as officers surrounded the van he was inside. A handgun was recovered from the van, which matched descriptions of the vehicle he used to get away from the dance studio.

Sheriff’s deputies from Los Angeles County searched Tran’s home in a gated senior community in the town of Hemet, a little over an hour’s drive from the site of the massacre.

Luna said his officers found a .308-caliber rifle, an unknown amount of bullets and evidence he was making homemade firearm suppressors that muffle the sound of the weapons.

Tran had visited Hemet police twice this month to report he was the victim of fraud, theft and poisoning by family members a decade or two ago in the LA area, Hemet police spokesperson Alan Reyes told The Associated Press. Tran said he would return to the station with documentation but never did.

The death toll rose to 11 Monday after health officials announced that one of the 10 people wounded had died, officials said.

My Nhan, 65, Lilian Li, 63, and Xiujuan Yu, 57, were identified by the Los Angeles coroner’s office as three of the six women killed. Two other women were in their 60s, and one was in her 70s. Valentino Alvero, 68, was the only man identified. Three men in their 70s and one in his 60s were also killed.

Nhan’s family said in a statement that she was a loving person whose kindness was contagious, and loved to dance.

“Unfairly, Saturday was her last dance,” the family said. “We are starting the Lunar New Year broken. We never imagined her life would end so suddenly.”

Authorities have shared little about Tran, who owned a trucking company in Monterey Park from 2002 to 2004, according to California business records.

He was once arrested for unlawful possession of a firearm in 1990 and had a limited criminal history, Luna said. The sheriff could not immediately say if a gun arrest at a time when firearms laws were different would have barred him from owning weapons.

Tran’s ex-wife told CNN they married soon after they met at Star Ballroom, where he offered her free lessons. She said he would become upset if she missed a step dancing, but was never violent toward her.

They divorced five years later, citing irreconcilable differences, Los Angeles Superior Court records show. The couple did not have children, said they had no community property and neither side had to pay alimony.

While she is named in court papers, she asked not to be identified because of the sensitivity of the case.

His ex-wife’s story was echoed by a friend who told AP that Tran offered to teach new women at both clubs how to dance for free so that he would have a partner.

But Tran was perpetually distrustful and paranoid and would regularly complain that people at the clubs didn’t like him, according to the former friend who requested anonymity to speak about Tran because he wanted to avoid the media spotlight.

“He always cast a dubious eye toward everything. He just didn’t trust people at all,” the friend said. “He always complained to me that the instructors … kept distance from him, and according to what he said, many people spoke evil of him.”

Tran eventually moved from the San Gabriel Valley, a melting pot for Asian immigrants, and settled in Hemet, a lower-income community of many retirees 75 miles (120 kilometers) east of Los Angeles in Riverside County.

Tran lived in The Lakes at Hemet West, a gated community off a busy road with a view of snow-covered mountains. The development has a par-3 golf course, shuffleboard court and a dance floor. Properties listed for sale ranged from $45,000 to $222,000.

A neighbor, Pat Roth, told KNBC-TV that Tran said he was a ballroom dance instructor in the past and would sometimes show up to dances at the senior community.

“Didn’t seem like he’d harm a fly, you know. He wasn’t a big guy,” Roth said. “He’d pet your dog when you walked by.”

Hemet police had no records of any incidents involving Tran in the community or calls for service at his home, Reyes said.

The shootings during Lunar New Year celebrations sent a wave of fear through Asian American communities, dealing another blow to a community that has been the target of high-profile violence in recent years and cast a shadow over festivities nationwide.

The massacre was the nation’s fifth mass killing this month and the deadliest attack since May 24, when 21 people were killed in an elementary school in Uvalde, Texas.

Tran is the second-oldest mass killer in the U.S. over the last nearly 20 years according to a database compiled by The Associated Press, USA Today and Northeastern University. The only older mass killer was a 73-year-old who murdered five people in Yuma County Arizona in 2011 before killing himself. The database tracks every mass killing — defined as four dead not including the offender — committed in the U.S. since 2006.

About 20 minutes after the first attack in Monterey Park, Tran entered the Lai Lai Ballroom in the nearby city of Alhambra.

Tsay, who was in the lobby, 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.

“He saw that he had an opportunity,” said his father, Tom Tsay, co-owner of the studio. “The person was cocking his gun. And he saw the opportunity and he just jumped.”

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This story has been corrected to show that Tran had a previous arrest for unlawful possession of a firearm, not a conviction.

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Taxin reported from Hemet, Dazio reported from Alhambra and Melley reported from Los Angeles. Associated Press journalists Alanna Durkin Richer in Boston, Christopher Weber, John Antczak and Robert Jablon in Los Angeles, and Julie Watson in San Diego contributed to this report.