Los Angeles county sheriff Robert Luna said during a press conference the motive for the shooting was not known. He identified the suspect as Huu Can Tran, 72, who wielded a pistol with a high-capacity magazine.
"We want to know how something this awful can happen," Luna told reporters.
Luna said Tran turned a handgun on himself on Sunday morning as police approached a white van he was driving in Torrance, about 34km from the site of the shooting at the Star Ballroom Dance Studio in Monterey Park.