The man was under a "mental health-based prohibition" but was listed in the state's Armed Prohibited Persons System database as owning one firearm, according to a statement from the attorney general's office.
CALIFORNIA GOV. GAVIN NEWSOM ENDORSES EVEN STRICTER GUN CONTROL AFTER STRING OF MASS SHOOTINGS
Nearly two dozen guns and thousands of rounds of ammunition are displayed following an arrest on Jan. 25, 2023, in Azusa, California. The guns were seized from the home of a man who had mental health problems. (California's Attorney General's Office via AP)
The database identifies people who legally held firearms but were later banned from having them.
Authorities went to the man's home to seize the gun but he refused to let them in, the statement said.
After getting a search warrant, agents entered and found "four machine guns, seven assault weapons, a short-barreled rifle, four suppressors/silencers, six handguns, one shotgun, four rifles, 54 lower receivers/frames, 41 standard capacity magazines, 87 large-capacity magazines, and approximately 35,000 rounds of miscellaneous ammunition," the statement said.
The statement didn't identify the man or why he was placed under a mental health-related weapons prohibition.
The man is charged with various crimes relating to unlawful possession of guns, silencers and ammunition, authorities said.