The weapons seen in aerial footage and police photos appeared to include at least eight AR-15 style rifles, a .22 handgun with a silencer, an Uzi with silencer, two Thompson submachine guns, sawed-off shotguns and guns with barrels made too short to comply with California law.
That's according to a weapons expert who reviewed photos and video of the weapons confiscated from the home Wednesday.
The expert observed at least 17 weapons that appear to be illegal.
"ATF will probably be initiating traces on those and they can find out if they're stolen," said Greg Block with the site Firearmstraining.com.
One weapon was imprinted with Armeria de Saenz - the Spanish word for armory and the last name of the suspect.
Girard Damien Saenz, 57, was arrested after the LAPD and ATF served a search warrant at the home on Beverly Glen following an anonymous tip about someone selling or manufacturing weapons out of the home.
Saenz was booked on at least one weapons charge and may face additional charges later as authorities continue to investigate the stockpile.
Los Angeles police and federal agents seized more than 1,000 firearms and thousands of rounds of ammunition after executing a search warrant at the home.
Around the same time as the search warrant was executed at the Holmby Hills property, officers were also carrying out a search of a property in Chinatown that is believed to be connected.
Neighbors say the SWAT team waited outside the property more than an hour to determine if anyone was inside before forcibly entering the home. It appears that property was not occupied. There was no word on what was seized from the Chinatown location.
Saenz shows up on property records for the Holmby Hills home alongside Cynthia Beck, a former mistress to Gordon Getty, one of the world's richest men. It is unclear how Saenz and Beck are connected.
Neighbors say they believe Saenz has lived at the property for nearly 20 years.
Saenz was released on $50,000 bail Thursday morning.
The weapons were found stacked all around the home, described as a large house with multiple rooms that was cluttered with guns and ammunition.
They were described as a wide range of makes and models - assault weapons, rifles, shotguns and handguns - of different ages.
Many were modern and some went back 50 years or more. A few were even collectibles that dated back to the Civil War.
"I had never seen so many weapons in my career of 31 years," said LAPD Lt. Chris Ramirez. "That's such a big arsenal in a residence like this, in this type of neighborhood. It's astounding."
Ramirez noted it is not illegal for someone to own a large collection of firearms. But he said it is illegal to sell weapons from one's home without going through the extensively regulated state and federal processes.
Saenz was the only person home and the only person taken into custody.
Holmby Hills is a small, wealthy neighborhood in the hills northeast of UCLA that is perhaps best known as the home of the Playboy Mansion.
Neighbors were appalled to hear about the discovery and arrest.
"I would never, ever think anybody would be wanting to pack so much in this neighborhood. It scares the wits out of you," said Rabbi Chaim Mentz. "What does my next-door neighbor have? What does your next-door neighbor have?"