Thousands of federal agents raided businesses in downtown L.A.’s Fashion District on Wednesday and seized an estimated $65 million as part of a crackdown on what is alleged to be a sophisticated money laundering operation by Mexican drug cartels.

Nine people were arrested and stacks of cash were seized from Fashion District businesses. The businesses searched were suspected of laundering narcotics profits using so-called “Black Market Peso Exchange” schemes in which bags crammed with dollars are dropped off at American businesses and then systematically distributed to a number of banks in deposits less than $10,000 each, to avoid regulatory reporting requirements.

“Los Angeles has become the epicenter of narco-dollar money laundering with couriers regularly bringing duffel bags and suitcases full of cash to many businesses,” said Assistant U.S. Attorney Robert E. Dugdale, who oversees the Criminal Division in the Central District of California, in a statement.

The raids coincided with the unsealing of three indictments. The most serious of them alleges that the Sinaloa Drug Cartel used Q.T. Fashion Inc., a maternity wholesaler in the Fashion District, to accept and launder ransom payments.

The cartel kidnapped and tortured a U.S. citizen after federal agents seized more than 100 kilograms of cocaine that he was responsible for distributing, the indictment claims. The victim was held at a ranch in Mexico where he was beaten, shot, electrocuted and waterboarded – while his relatives hustled to pay $140,000 in ransom for his release, a sum which was allegedly delivered to Q.T. Fashion.

“Today’s arrests and searches should send a message to international drug cartels that the FBI and our partners won’t tolerate the exploitation of American business for the purposes of illicit financial transactions and that fund hostage-taking and the distribution of narcotics,” Bill L. Lewis, the assistant director of the Federal Bureau of Investigation’s Los Angeles unit, said in a statement.

The indictments also accuse three other Fashion District businesses – Gayima Underwear, Yili Underwear, and Pacific Eurotex Corp. – of laundering drug cartel money.