Jeanine John Taele, 38, was detained by Los Angeles County sheriff’s officers after being seen taking pictures and sussing security activities at the golf course on Sunday at around 3.30pm.
The incident came before Trump was due to host a Republican National Committee fundraising dinner at the golf club in the Rancho Palos Verdes suburb on Tuesday.
Police discovered a loaded magazine in Taele’s pocket, the LA Times reported.
They also found a loaded pistol and further ammunition in his car.
On Monday a further search at the 38-year-old’s property in Downey, California led to police finding more weapons and ammunition, including a .45 caliber pistol, body armour and high-capacity magazines.
The police noted they also discovered several notebooks with ‘concerning statements’ in as well as two radio devices.
Taele was arrested under suspicion of carrying a concealed firearm and possession of illegal ammunition, including hollow point bullets.
Police have launched an investigation and have claimed there is ‘no credible threat to our communities.’
Taele is also under investigation in connection with a robbery in nearby El Segundo.
The Express have reached out to the White House for comment.