Prosecutors have asked for the man to be held on a $2 million bail after charging him with a felony weapons violation. Authorities said there are no known links to the Orlando shooting at a gay nightclub.
Los Angeles prosecutors on Tuesday charged 20-year-old James Wesley Howell of Indiana with unlawful possession of an assault weapon and explosives.
Prosecutors asked that Howell be held on $2 million (1.78 million euro) bail.
Police arrested Howell on Sunday after they found him in his car with three assault rifles and high-capacity magazines. Authorities also discovered chemicals that could be used to create an explosive device.
"The suspect did make an initial statement to the effect that he was going to go to the pride festival," Santa Monica Police Lieutenant Saul Rodriguez told reporters on Sunday.
"Beyond that he did not make any additional statement saying that he was going to do anything further than that. We do not have any additional information related to what his intentions were," Rodriguez added.
Santa Monica Police Chief Jacqueline Seabrooks said there is no known link between Howell and Omar Mateen, who killed 49 people and injured 53 more when he attacked a gay nightclub in Orlando on Sunday.
An FBI spokesman said agents are working with local authorities in the US state of Indiana, where they executed a search warrant of Howell's Clark County residence.
ls/bw (AP, Reuters)