The thieves forced their way into the building and broke into the safe where the money was kept, Los Angeles Police Commander Elaine Morales told the Los Angeles Times, which broke the news of the crime.
The operators of the business only noticed the gigantic theft, equivalent to around 27.7 million euros, when they opened the safe again.
Local media identified the stolen premises as the headquarters of GardaWorld, a global cash security management company, which also operates a fleet of armored cash-in-transit cars, but the company did not respond to a request for confirmation by the Associated Press.
On Thursday, city police and the FBI said only that they are jointly investigating the robbery "to determine the person or group responsible", without providing details about the amount stolen or the name of the company.
The Times reported that the robbery was one of the largest cash heists in the city's history and surpassed any armored car robbery in Los Angeles.
Almost two years ago, around 100 million dollars in jewelry and other valuables were stolen from a Brink's big rig in Southern California. The perpetrators of this theft were never caught.
