The shooter was 72-year-old Hu Kang Tran, according to RIA Novosti.
"I can confirm that there are no other suspects in the Monterey Park mass shooting incident," the sheriff said.
It is noted that the body was found in a truck 50 miles from the scene.
Work on establishing the motives of the perpetrator continues.
Earlier, US President Joe Biden expressed his condolences in connection with the mass shooting in California.