Update: 130 people were arrested and 60 bank branches across California were visited by officers from several different local departments, one of which included armed patrolmen, as the reason for the intensive patrols was explained.
The authorities say the money is now back with its rightful owners and nobody was harmed during the operation.
A truck carrying bags of money became stuck in traffic on a major California freeway and triggered a $20 million cash-grab spree.
Banks across the state were visited by officers who confiscated thousands of dollars in cash after reporting that bags of cash had been seen dropping onto the 5 Freeway near Moorpark in Los Angeles.
The notes were said to be part of a $20 million illegal cash-grab organised by the Mexican Mafia gang, reports LA Weekly.
Pictures taken at the scene show cardboard boxes filled with money falling from the top of a vehicle.
A branch of a southern California bank was visited by police officers on Saturday (4 Oct) who said they had recovered at least $3 million.
The mysterious incident was reported to local authorities who then said they were co-ordinating with the US Marshals Service to find the other $20 million.
“It’s a big-city operation,” a police spokeswoman told LA Weekly, with the Los Angeles Police Department getting involved in the investigation.
The money was reportedly arranged by Los Angeles-based real estate investors who were spending it to help fund a gang’s activities.
Investigators now believe the bags of money were dropped off by men driving an armoured vehicle.
The cash-grab ran into problems after the truck was stuck in traffic, causing it to lose its load.
The bags were later returned to their owner – described as a “marijuana company” by police – along with the American flag and an internal van.
“There were no robberies and no shots fired,” an LAPD official said.
“There is no evidence anyone was targeted or committed violent crimes because of the cash they found.”
The incident began when vehicles spotted bags of cash on the side of the road and alerted officers.