Investigators discovered hundreds of rounds of ammunition and a rifle in the home of the man accused of shooting and killingand wounding others in Police also recovered 42 shell casings at the scene of the shooting.
Investigators said the 72-year-old suspect, Huu Can Tran, had a criminal history including a 1990 arrest for unlawful possession of a firearm.
Records show the suspect, who lived more than an hour from the site of the shooting, visited California's Hemet Police Station twice this month alleging he was the victim of fraud, theft and poisoning involving his family more than a decade ago.
Pat Roth, the shooter's neighbor, told CBS News the suspect didn't strike him "as having an angry bone in his body."
The gunman unleashed his attack while people were celebrating the Lunar New Year at the Star Ballroom Dance Studio in Monterey Park on Saturday night. Police believe he was attempting to carry out a second attack when he was disarmed by a man who helps operate the family-owned Lai Lai Ballroom in Alhambra, California.
A motive for the shooting remains unknown. A second handgun was found in the van where the suspect died of a self-inflicted gunshot wound.
Brandon Tsay was in the lobby of a dance hall when he came face to face with the suspect. He said he didn't hesitate to jump into action and wrestle the weapon away from the shooter. Surveillance footage captured the struggle.
"I realized in the moment that I needed to do something," he told CNN.
Los Angeles County Sheriff Robert Luna said Monday at a press conference that Tsay's heroic actions
The massacre was the nation's fifth mass killing this month. The death toll stood at 10 on Sunday, but rose to 11 on Monday afternoon when one of the wounded victims died of injuries.
One victim has been identified as 65-year-old Mymy Nhan.
Nhan's niece, Fonda Quan, said Nhan was a regular at the Star Ballroom for more than a decade. Nhan was leaving the studio to prepare to celebrate the Lunar New Year — just as the gunman was arriving. She was shot in her vehicle.
Quan said Saturday was Nhan's first time dancing in three weeks, since the death of her mother.
"She was particularly excited about it. And, you know, it's, unfortunately, her last dance," Quan said.
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